Warning

 

Close

Confirm Action

Are you sure you wish to do this?

Confirm Cancel

Log In

A valid email is required.
Password is required.
Site Notices
Basic
  • Joined Feb 2013
  • Posts 103
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 103
  • Location USA CA, USA
Offline
Posted: 7/14/2013 10:54:27 AM EST
[Last Edit: 7/14/2013 11:45:48 AM EST by Xcountryrider]
Ar15performace.com is working on a new cartridge for the AR-15 platform that promises to deliver game changing performance. If your thinking that sounds like a 6.8SPC think again. The 270AR will deliver at 200FPS more velocity from any barrel length compared to 6.8SPC. That 200FPS boost pretty much over comes the advantage that the 6.5 Grendel has in long range over the 6.8SPC. In other words this new cartridge will threaten the argument for getting either cartridge. Not that the 6.8SPC and 6.5 Grendel shops will pack up and go home this is a wildcat cartridge and will only be for home hand loaders.

Hand loaders should be able to load from 85gr to 140gr bullets making the cartridge applicable for varmints to medium sized game such a hogs, deer, antelope and caribou. I would expect some of the more adventurous to go after Elk with 140gr Berger VLD's. I don't have velocities for a 140 gr but even if we assume 2700FPS which is a low estimate we are in the big game range for Elk according to HITS. I know many traditional hunters think a .270 is to small for Elk but many Elk have been taken with a .270. Chuck Hawks tackles this subject here saying the 270 is adequate in his opinion but acknowledge's many hunters consider it an ideal ELK caliber. The 270AR though is not an equivalent to a 270 bolt. As much as the 270AR has on the 6.8SPC the 270 bolt has on the 270AR. Still expect to hear Elk stories in the future from 270AR hunters.

The parent brass will be 6.5 Lapua or 6.5 Creedmore. The 6.5 Lapua is the preferred brass because its thinner and will hold more powder. The 6.5 Creedmore will maybe have a 50 FPS drop in performance from the Lapua due to less powder capacity according to the designers estimates. Hand loaders will take these parent brass cases and cut them down and reshape them using a modified 6.5 lapua reshaping die. No complicated fire forming required. This process will be very similar to what hand loaders are doing now with 5.56mm brass to make it 300 Blk brass.

From a 18in barrel the Hornady 120gr SST is going at 2860FPS and the 130g Berger VLD is getting around 2800FPS from a 20in barrel. The designer estimates that a 110gr bullet should be at or close to 3000FPS. Typically a 6.5mm Grendel max powder capacity is around 29gr compared to around 39gr of powder for the 270AR. This added push out the barrel makes up for the higher BC that the 6.5mm enjoys giving the 270AR much lower drops over long distance shooting. I put together a chart to compare the Grendel to the 270AR shooting 130gr bullets. I couldn't find numbers of a 6.8SPC for the 130gr to do a comparison for this gr size. Be mindful of the barrel length in this comparison because the Grendel has a 4 in barrel length advantage in this data. Read more at the the parent thread over at the 6.8SPC forum. ar15performance.com will be selling the barrels and bolt combos for 400 bucks.




Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1047
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1047
  • Location USA VA, USA
Offline
Link Posted: 7/14/2013 11:17:55 AM EST
Dang!! If the drop at 1000 is accurate that is pretty nasty!
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Basic
  • Joined Feb 2013
  • Posts 104
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 104
  • Location USA CA, USA
Offline
Link Posted: 7/14/2013 11:20:45 AM EST
Originally Posted By ilovebullets:
Dang!! If the drop at 1000 is accurate that is pretty nasty!


I used this ballistic calc to run the numbers. http://www.handloads.com/calc/
Member
Avatar
Platinum
  • Joined Apr 2008
  • Posts 5041
  • Location AFG AFG
Online
Platinum
  • Joined Apr 2008
  • Posts 5041
  • Location AFG AFG
Online
Military
Link Posted: 7/14/2013 11:27:36 AM EST
Your links don't work
The government's view of the economy could be summed up in a few short phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.

Ronald Reagan
Basic
  • Joined Feb 2013
  • Posts 105
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 105
  • Location USA CA, USA
Offline
Link Posted: 7/14/2013 11:42:04 AM EST
fixed thanks
Come and Take It
Avatar
Bronze
  • Joined Feb 2008
  • Posts 5629
  • Location USA GA, USA
Offline
Bronze
  • Joined Feb 2008
  • Posts 5629
  • Location USA GA, USA
Offline
Link Posted: 7/14/2013 1:38:40 PM EST
Bullet drop and velocity is not the most important factor to look at when comparing long range cartridges. It is a constant and will have to be accounted for no matter what you are shooting. What matters is wind deflection and stability. Will it beat all the other cartridges in other aspects?
John 8:12 "I am the light of the world: he that followeth me shall not walk in darkness, but shall have the light of life."
Basic
  • Joined May 2004
  • Posts 1351
  • Location USA NH, USA
Offline
Basic
  • Joined May 2004
  • Posts 1351
  • Location USA NH, USA
Offline
Link Posted: 7/14/2013 5:56:52 PM EST
It is still a little early to tell on this cartridge, H is just discussing it over on the 68 forums, this will be basically a step up in hunting cartridges for the AR15 platform.

It is an interesting project and once the rifles get built we will know more info on how it will work out.
Member
Avatar
Platinum
  • Joined Apr 2008
  • Posts 5048
  • Location AFG AFG
Online
Platinum
  • Joined Apr 2008
  • Posts 5048
  • Location AFG AFG
Online
Military
Link Posted: 7/14/2013 6:40:04 PM EST
Looks interesting I might have to wait on building a 6.5 and see how the 270AR pans out.
The government's view of the economy could be summed up in a few short phrases: If it moves, tax it. If it keeps moving, regulate it. And if it stops moving, subsidize it.

Ronald Reagan
Member
Avatar
Bronze
  • Joined Jan 2011
  • Posts 1698
  • Location USA IA, USA
Offline
Bronze
  • Joined Jan 2011
  • Posts 1698
  • Location USA IA, USA
Offline
Link Posted: 7/15/2013 3:45:35 AM EST
Looks like i found my next wildcat for the lonely upper in my tool box.
Member
Avatar
Bronze
  • Joined Oct 2010
  • Posts 5800
  • Location USA WI, USA
Offline
Bronze
  • Joined Oct 2010
  • Posts 5800
  • Location USA WI, USA
Offline
Link Posted: 7/15/2013 5:41:29 AM EST
[Last Edit: 7/15/2013 7:16:55 AM EST by Clarinath]
Your comparison is for two very different bullets. A VLD against an Accubond BT? Kinda one sided.

If the Grendel only has a case capacity of 29 gr, how on earth am I cramming 31.2 gr of Win 748 in that little case?

And I have a 20" barrel, not 24.

I can't post my ballistics chart so if anyone has any idea how to do it, let me know.
Carpe Noctem
A man dies twice. Once when the breath leaves his body and again when the last person who knew him speaks his name for the last time.
Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1054
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1054
  • Location USA VA, USA
Offline
Link Posted: 7/15/2013 10:56:19 AM EST
Originally Posted By Clarinath:
Your comparison is for two very different bullets. A VLD against an Accubond BT? Kinda one sided.

If the Grendel only has a case capacity of 29 gr, how on earth am I cramming 31.2 gr of Win 748 in that little case?

And I have a 20" barrel, not 24.

I can't post my ballistics chart so if anyone has any idea how to do it, let me know.


748 is ball powder isn't it?? That's a lot of powder. Curious as to what kind of velocity you are getting. I am using 28.3 grains of 8208XBR over a CCI 450 and under a 123 AMAX. I haven't gotten to chrono due to lack of having one but I get really good groups. I have a 24" Grendel and doubt I would fool with another "odd" cartridge. I'm not saying they are bad, just sucks trying to hunt down parts for the wildcats.
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4442
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4442
  • Location USA UT, USA
Offline
Link Posted: 7/15/2013 11:35:05 AM EST
[Last Edit: 7/15/2013 11:55:29 AM EST by LRRPF52]
How about comparing a 20" Grendel to a 20" .270AR SPR using the 130gr VLD for both?

6.5 Grendel 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .582 BC G1, 2450fps mv

       Range    Velocity    Energy     Trajectory         TOF          Drift

(yards) (fps) (ft-lb) (inches) (sec) (inches)
0 2450 1733 -2.50 0.0000 0.00
100 2303 1530 0.00 0.1263 -0.68
200 2160 1347 -4.06 0.2608 -2.81
300 2023 1181 -15.59 0.4043 -6.52
400 1891 1032 -35.61 0.5577 -11.97
500 1765 899 -65.37 0.7219 -19.32
600 1645 781 -106.30 0.8979 -28.76
700 1533 678 -160.09 1.0869 -40.48
800 1428 588 -228.71 1.2897 -54.64
900 1332 512 -314.40 1.5074 -71.41
1000 1247 449 -419.70 1.7403 -90.87


270 ARP, 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .452 BC G1, 2775fps

       Range    Velocity    Energy     Trajectory         TOF          Drift

(yards) (fps) (ft-lb) (inches) (sec) (inches)
0 2775 2223 -2.50 0.0000 0.00
100 2572 1909 -0.00 0.1123 -0.74
200 2377 1631 -2.77 0.2336 -3.08
300 2192 1386 -11.70 0.3651 -7.19
400 2014 1171 -27.89 0.5078 -13.30
500 1846 984 -52.66 0.6634 -21.66
600 1688 822 -87.67 0.8334 -32.55
700 1540 685 -134.91 1.0195 -46.29
800 1406 571 -196.84 1.2235 -63.17
900 1288 479 -276.38 1.4466 -83.42
1000 1187 407 -376.92 1.6895 -107.16


The .270 ARP will keep the bullet over 1800fps longer, because it starts with over 300fps more mv. Neck the .270 ARP down to 6.5mm and you have something really cool, especially with the new Nosler Accubond Long-Range 129gr ABLR with a .562 BC. Pushing that from an AR15 at 2700fps would make a great hunting rifle for the few people that are capable of exploiting those ballistics at distance. Look at the wind drift between the two as well. It shows that a Grendel still beats a .270 Berger 130gr going over 300fps faster.

For everyone else, the Grendel and 6.8 do just fine as off-the-shelf solutions for your common hunting distances. That said, a 22" Grendel has been used to kill Antelope at 752yds by an experienced long-range hunter using the 123gr A-MAX.

There is another wildcat cartridge that will push a 140gr 6.5mm from an AR15 faster than a .260 Rem can from an AR10. Pressure-testing has already achieved 3200fps with a 140gr 6.5mm.

I still applaud the evolution of AR15-compatible, high-performance cartridges like the .270 ARP that offer hunters and competitors more options from a ubiquitous, lightweight rifle frame that continues to serve us well. It's great to have currently-available, low-recoil solutions that even my kids can hunt with, that maintain a lot of energy downrange.
Basic
  • Joined Mar 2011
  • Posts 4505
  • Location USA OR, USA
Offline
Basic
  • Joined Mar 2011
  • Posts 4505
  • Location USA OR, USA
Offline
Link Posted: 7/15/2013 12:24:54 PM EST
Originally Posted By LRRPF52:
How about comparing a 20" Grendel to a 20" .270AR SPR using the 130gr VLD for both?

6.5 Grendel 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .582 BC G1, 2450fps mv

       Range    Velocity    Energy     Trajectory         TOF          Drift      (yards)     (fps)     (ft-lb)     (inches)         (sec)       (inches)          0      2450        1733          -2.50         0.0000         0.00        100      2303        1530           0.00         0.1263        -0.68        200      2160        1347          -4.06         0.2608        -2.81        300      2023        1181         -15.59         0.4043        -6.52        400      1891        1032         -35.61         0.5577       -11.97        500      1765         899         -65.37         0.7219       -19.32        600      1645         781        -106.30         0.8979       -28.76        700      1533         678        -160.09         1.0869       -40.48        800      1428         588        -228.71         1.2897       -54.64        900      1332         512        -314.40         1.5074       -71.41       1000      1247         449        -419.70         1.7403       -90.87


270 ARP, 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .452 BC G1, 2775fps

       Range    Velocity    Energy     Trajectory         TOF          Drift      (yards)     (fps)     (ft-lb)     (inches)         (sec)       (inches)          0      2775        2223          -2.50         0.0000         0.00        100      2572        1909          -0.00         0.1123        -0.74        200      2377        1631          -2.77         0.2336        -3.08        300      2192        1386         -11.70         0.3651        -7.19        400      2014        1171         -27.89         0.5078       -13.30        500      1846         984         -52.66         0.6634       -21.66        600      1688         822         -87.67         0.8334       -32.55        700      1540         685        -134.91         1.0195       -46.29        800      1406         571        -196.84         1.2235       -63.17        900      1288         479        -276.38         1.4466       -83.42       1000      1187         407        -376.92         1.6895      -107.16


The .270 ARP will keep the bullet over 1800fps longer, because it starts with over 300fps more mv. Neck the .270 ARP down to 6.5mm and you have something really cool, especially with the new Nosler Accubond Long-Range 129gr ABLR with a .562 BC. Pushing that from an AR15 at 2700fps would make a great hunting rifle for the few people that are capable of exploiting those ballistics at distance. Look at the wind drift between the two as well. It shows that a Grendel still beats a .270 Berger 130gr going over 300fps faster.

For everyone else, the Grendel and 6.8 do just fine as off-the-shelf solutions for your common hunting distances. That said, a 22" Grendel has been used to kill Antelope at 752yds by an experienced long-range hunter using the 123gr A-MAX.

There is another wildcat cartridge that will push a 140gr 6.5mm from an AR15 faster than a .260 Rem can from an AR10. Pressure-testing has already achieved 3200fps with a 140gr 6.5mm.

I still applaud the evolution of AR15-compatible, high-performance cartridges like the .270 ARP that offer hunters and competitors more options from a ubiquitous, lightweight rifle frame that continues to serve us well. It's great to have currently-available, low-recoil solutions that even my kids can hunt with, that maintain a lot of energy downrange.

Gonna need some backup on that one.
Until then, it's just talk.

Member
Avatar
Bronze
  • Joined Jan 2011
  • Posts 1700
  • Location USA IA, USA
Offline
Bronze
  • Joined Jan 2011
  • Posts 1700
  • Location USA IA, USA
Offline
Link Posted: 7/15/2013 12:33:17 PM EST
Originally Posted By LRRPF52:

The .270 ARP will keep the bullet over 1800fps longer, because it starts with over 300fps more mv. Neck the .270 ARP down to 6.5mm and you have something really cool, especially with the new Nosler Accubond Long-Range 129gr ABLR with a .562 BC. Pushing that from an AR15 at 2700fps would make a great hunting rifle for the few people that are capable of exploiting those ballistics at distance. Look at the wind drift between the two as well. It shows that a Grendel still beats a .270 Berger 130gr going over 300fps faster.

For everyone else, the Grendel and 6.8 do just fine as off-the-shelf solutions for your common hunting distances. That said, a 22" Grendel has been used to kill Antelope at 752yds by an experienced long-range hunter using the 123gr A-MAX.

There is another wildcat cartridge that will push a 140gr 6.5mm from an AR15 faster than a .260 Rem can from an AR10. Pressure-testing has already achieved 3200fps with a 140gr 6.5mm.

I still applaud the evolution of AR15-compatible, high-performance cartridges like the .270 ARP that offer hunters and competitors more options from a ubiquitous, lightweight rifle frame that continues to serve us well. It's great to have currently-available, low-recoil solutions that even my kids can hunt with, that maintain a lot of energy downrange.



I would like to see the proof of that one. 140gn bullet at 3200fps in a round that fits the ar15 I will call bs on this one till it is proved
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4444
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4444
  • Location USA UT, USA
Offline
Link Posted: 7/15/2013 12:56:59 PM EST
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.
fuego antipático
Avatar
Lifetime Member
  • Joined Jan 2003
  • Posts 3580
  • Location USA WA, USA
Offline
Lifetime Member
  • Joined Jan 2003
  • Posts 3580
  • Location USA WA, USA
Offline
Link Posted: 7/15/2013 1:30:37 PM EST

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.
The only fool bigger than the person who knows it all is the person who argues with him. Stanislaw Jerszy Lec
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4450
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4450
  • Location USA UT, USA
Offline
Link Posted: 7/15/2013 4:17:11 PM EST
[Last Edit: 7/15/2013 4:19:54 PM EST by LRRPF52]
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I just did a sanity check, and the .264 Win Mag maxes out at 3000fps with 140gr.

The guys doing the testing did mention over-pressure testing, so maybe the 3200fps was achieved when they tested the max case pressure. The cases didn't fail, but the brass was trash of course.

The case uses a rebated rim to .473", with a much fatter body. Case capacity is well over 40 grains. They said the pressure-safe loads were definitely beating .260 Remington with 140gr.

Cases like the .270 ARP, .30 RAR necked down, and some other wildcats that will provide magnum performance from an AR15 will simply help promote the increasing popularity of the AR15 as an even more viable hunting system into the future.
Basic
  • Joined Feb 2013
  • Posts 106
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 106
  • Location USA CA, USA
Offline
Link Posted: 7/15/2013 4:54:21 PM EST
Compared to a 6.8SPC. The 6.8SPC has a 2in barrel advantage in this comparison.

Basic
  • Joined Feb 2013
  • Posts 107
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 107
  • Location USA CA, USA
Offline
Link Posted: 7/15/2013 6:00:32 PM EST
[Last Edit: 7/15/2013 6:07:18 PM EST by Xcountryrider]
Originally Posted By LRRPF52:
How about comparing a 20" Grendel to a 20" .270AR SPR using the 130gr VLD for both?

6.5 Grendel 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .582 BC G1, 2450fps mv

       Range    Velocity    Energy     Trajectory         TOF          Drift      (yards)     (fps)     (ft-lb)     (inches)         (sec)       (inches)          0      2450        1733          -2.50         0.0000         0.00        100      2303        1530           0.00         0.1263        -0.68        200      2160        1347          -4.06         0.2608        -2.81        300      2023        1181         -15.59         0.4043        -6.52        400      1891        1032         -35.61         0.5577       -11.97        500      1765         899         -65.37         0.7219       -19.32        600      1645         781        -106.30         0.8979       -28.76        700      1533         678        -160.09         1.0869       -40.48        800      1428         588        -228.71         1.2897       -54.64        900      1332         512        -314.40         1.5074       -71.41       1000      1247         449        -419.70         1.7403       -90.87


270 ARP, 20" Barrel, 2.5" Optic Height, 130gr Berger VLD, .452 BC G1, 2775fps

       Range    Velocity    Energy     Trajectory         TOF          Drift      (yards)     (fps)     (ft-lb)     (inches)         (sec)       (inches)          0      2775        2223          -2.50         0.0000         0.00        100      2572        1909          -0.00         0.1123        -0.74        200      2377        1631          -2.77         0.2336        -3.08        300      2192        1386         -11.70         0.3651        -7.19        400      2014        1171         -27.89         0.5078       -13.30        500      1846         984         -52.66         0.6634       -21.66        600      1688         822         -87.67         0.8334       -32.55        700      1540         685        -134.91         1.0195       -46.29        800      1406         571        -196.84         1.2235       -63.17        900      1288         479        -276.38         1.4466       -83.42       1000      1187         407        -376.92         1.6895      -107.16


The .270 ARP will keep the bullet over 1800fps longer, because it starts with over 300fps more mv. Neck the .270 ARP down to 6.5mm and you have something really cool, especially with the new Nosler Accubond Long-Range 129gr ABLR with a .562 BC. Pushing that from an AR15 at 2700fps would make a great hunting rifle for the few people that are capable of exploiting those ballistics at distance. Look at the wind drift between the two as well. It shows that a Grendel still beats a .270 Berger 130gr going over 300fps faster.

For everyone else, the Grendel and 6.8 do just fine as off-the-shelf solutions for your common hunting distances. That said, a 22" Grendel has been used to kill Antelope at 752yds by an experienced long-range hunter using the 123gr A-MAX.

There is another wildcat cartridge that will push a 140gr 6.5mm from an AR15 faster than a .260 Rem can from an AR10. Pressure-testing has already achieved 3200fps with a 140gr 6.5mm.

I still applaud the evolution of AR15-compatible, high-performance cartridges like the .270 ARP that offer hunters and competitors more options from a ubiquitous, lightweight rifle frame that continues to serve us well. It's great to have currently-available, low-recoil solutions that even my kids can hunt with, that maintain a lot of energy downrange.


Thats a nice comparison the 270AR has the grendel until 800 yards but if your ran it with the berger 130 gr for the .277 with a BC .497?

http://www.midwayusa.com/product/846190/berger-classic-hunter-hybrid-hunting-bullets-270-caliber-277-diameter-130-grain-hollow-point-boat-tail-box-of-100
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4462
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4462
  • Location USA UT, USA
Offline
Link Posted: 7/16/2013 11:06:35 AM EST
Yes, If I wanted the highest BC 130gr projectile without going to the solids and was pushing them down a .277" bore, the Berger 130 gr Match Grade Classic Hunter with .497 G1 BC would be somewhere near the top of the list, but as a target bullet.

Since there is no reason to lean .277 over .264, I'll stick with .264 pills. I have a .270 Winchester, but I only shoot it for fun maybe once a year with hand loads. I wish it was a .264 Win Mag or 6.5 Swede, but I won't alter it because it's a Pre-64 Model 70 Winchester that I got from my dad. It was the center-fire rifle I learned to shoot distance with as a kid, so there is a lot of sentimental value.

When I started shooting .308 extensively in the Army with the M24, I felt cheated compared to the .270's ballistics, but I didn't know much about 6.5mm back then. Something about going from a high BC bullet at around 3100fps down to a .30 cal pig going 2500fps didn't sit well with me for long-distance work. .308 never really excited me, except when considering a 7.62 NATO carbine of Stoner design.

.260 Rem and the Grendel kinda ruined my affection with .277 rifles and .308 carbines, although I still have a soft spot for the .270 Winchester.
Basic
  • Joined Jul 2012
  • Posts 80
  • Location USA AZ, USA
Offline
Basic
  • Joined Jul 2012
  • Posts 80
  • Location USA AZ, USA
Offline
Link Posted: 7/17/2013 3:41:40 AM EST
I prefer a 6.5mm, in a beefed-up AR-15 platform. To that end, I last week sent the following letter-appeal to Freedom Group, Inc. Chairman & C.E.O., George Kollitides:

"Dear Mr. Chairman:

I applaud the Remington Design Team for giving our sport shooting world the R-15 .30 Remington AR: a rifle with a robust AR-10 breech, in a lighter, shorter AR-15 platform. The concept is a long time coming. And, I dare state its arrival is welcomed by many.

So, at a time when rifles and ammunition 'are flying off the shelves,' why does a quick check of two major gun distributors, Budsgunshop.com and Grabagun.com, reveal that the Remington R-15, .30 RAR, is In stock, while other R-15 Models are Out of stock? And, a check of popular ammunition distributor, Midwayusa.com, shows that of the four products listed under .30 Remington AR, two are In stock, while many other calibers are Out of stock. I submit that the otherwise desirable R-15 .30 RAR platform is shackled by a cartridge, which downrange performance fails to impress, and which single-stack, low-capacity magazine and odd-sized case rim diameter both leave much to be desired.

In view of the above, let's consider a 21st Century-designed cartridge, with impressive downrange performance, that double-stacks in an AR-15 magazine and which case rim diameter, midway between the 5.56x45 and .30 Remington AR, is shared by other cartridges. Already impressive, in the standard AR-15 platform, its performance really shines in bolt-action rifles: the 6.5mm Grendel. Typical wait times for 6.5mm Grendel Barreled Upper Receivers are measured in months. And, a check with Midwayusa.com ammunition reveals that of the seven 6.5mm Grendel products, all, are Out of stock.

Let's compare the retained velocity, energy values of the .30 Remington AR, 150-grain Core-Lokt Pointed Soft Point (BC - 0.314), Muzzle Velocity - 2575 fps (24" test barrel), with the 6.5mm Grendel, 139-grain Lapua Scenar (BC - 0.615), Muzzle Velocity - 2305 fps (16" barrel AR-15) and 2700 fps (22" barrel bolt-action rifle), at 300, 400 and 500 yards:

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 yards . . . . . . . . . . . 400 yards . . . . . . . . . . 500 yards

24" R-15, .30 Remington AR: . . . 1804 fps/1084 ft-lb . . . 1588 fps/840 ft-lb . . . 1397 fps/650 ft-lb;
16" AR-15, 6.5mm Grendel . . . . . 1922 fps/1140 ft-lb . . . 1804 fps/1005 ft-lb . . . 1692 fps/884 ft-lb;
22" Bolt, 6.5 mm Grendel . . . . . . 2277fps/1600 ft-lb . . . 2147 fps/1423 ft-lb . . . 2020 fps/1259 ft-lb.

In short: the 6.5mm Grendel is a prime candidate chambering for the R-15 .30 RAR platform. Unencumbered by the penalties its increased bolt thrust on the smaller AR-15 Bolt impose, it can fly with the super-size AR-10 Bolt --- and, a 2.300" magazine, please!

Thank you for your consideration.

Sincerely,"

In retrospect, had Remington initally offered a 6.5/.30 RAR or a 6.5/450 Bushmaster in addition to/instead of the .30 Remington AR, that would have really stirred up the sport shooting world!
Basic
  • Joined Jul 2008
  • Posts 719
  • Location USA TX, USA
Offline
Basic
  • Joined Jul 2008
  • Posts 719
  • Location USA TX, USA
Offline
Link Posted: 7/17/2013 3:51:38 AM EST
man I would love a .30 ar necked down to 6.5.
Member
Avatar
Bronze
  • Joined Oct 2010
  • Posts 5802
  • Location USA WI, USA
Offline
Bronze
  • Joined Oct 2010
  • Posts 5802
  • Location USA WI, USA
Offline
Link Posted: 7/17/2013 6:36:58 AM EST
[Last Edit: 7/17/2013 6:38:15 AM EST by Clarinath]
Originally Posted By ilovebullets:
Originally Posted By Clarinath:
Your comparison is for two very different bullets. A VLD against an Accubond BT? Kinda one sided.

If the Grendel only has a case capacity of 29 gr, how on earth am I cramming 31.2 gr of Win 748 in that little case?

And I have a 20" barrel, not 24.

I can't post my ballistics chart so if anyone has any idea how to do it, let me know.


748 is ball powder isn't it?? That's a lot of powder. Curious as to what kind of velocity you are getting. I am using 28.3 grains of 8208XBR over a CCI 450 and under a 123 AMAX. I haven't gotten to chrono due to lack of having one but I get really good groups. I have a 24" Grendel and doubt I would fool with another "odd" cartridge. I'm not saying they are bad, just sucks trying to hunt down parts for the wildcats.


My velocities are right around 2680 give or take 20 on either side.

And I load the 123 Sierra MK for hunting and target shooting.

(Yes, I know I am not supposed to use MK bullets for hunting. I have been for years and have never lost an animal)
Carpe Noctem
A man dies twice. Once when the breath leaves his body and again when the last person who knew him speaks his name for the last time.
Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1071
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1071
  • Location USA VA, USA
Offline
Link Posted: 7/17/2013 6:03:49 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Clarinath:


My velocities are right around 2680 give or take 20 on either side.

And I load the 123 Sierra MK for hunting and target shooting.

(Yes, I know I am not supposed to use MK bullets for hunting. I have been for years and have never lost an animal)
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Clarinath:
Originally Posted By ilovebullets:
Originally Posted By Clarinath:
Your comparison is for two very different bullets. A VLD against an Accubond BT? Kinda one sided.

If the Grendel only has a case capacity of 29 gr, how on earth am I cramming 31.2 gr of Win 748 in that little case?

And I have a 20" barrel, not 24.

I can't post my ballistics chart so if anyone has any idea how to do it, let me know.


748 is ball powder isn't it?? That's a lot of powder. Curious as to what kind of velocity you are getting. I am using 28.3 grains of 8208XBR over a CCI 450 and under a 123 AMAX. I haven't gotten to chrono due to lack of having one but I get really good groups. I have a 24" Grendel and doubt I would fool with another "odd" cartridge. I'm not saying they are bad, just sucks trying to hunt down parts for the wildcats.


My velocities are right around 2680 give or take 20 on either side.

And I load the 123 Sierra MK for hunting and target shooting.

(Yes, I know I am not supposed to use MK bullets for hunting. I have been for years and have never lost an animal)


I use the 123 AMAX for hunting. I know they don't expand like a true hunting bullet but they have always done the job. Now that the 123 SST's are out I'm gonna try them this year. Another Arfcommer and I picked up a few boxes as soon as they hit the shelves.
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Basic
  • Joined May 2004
  • Posts 1354
  • Location USA NH, USA
Offline
Basic
  • Joined May 2004
  • Posts 1354
  • Location USA NH, USA
Offline
Link Posted: 7/17/2013 6:09:46 PM EST
Its really great how all these threads turn into "the 6.5 is the best bullet on the planet for all applications"

Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1072
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1072
  • Location USA VA, USA
Offline
Link Posted: 7/17/2013 6:25:18 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By marinesg1012:
Its really great how all these threads turn into "the 6.5 is the best bullet on the planet for all applications"

View Quote


Its even greater when nothing like that was said and somebody jumps in to assume. No chest bumping going on. Started off with here is a .270 bullet with highest BC versus a 6.5 bullet with low BC. Then Clarinath and LRRPF52 come in to show that the Accubond BT is a low BC bullet when compared to most 6.5 bullets. Then the numbers are reran and the bullet OP is talking about doesn't look so bad ass after all. Its not the Grendel's fault. I simply said I wouldn't pursue the cartridge because the last thing I wanna do is hunt for impossible to find parts again.
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Basic
  • Joined Feb 2013
  • Posts 108
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 108
  • Location USA CA, USA
Offline
Link Posted: 7/17/2013 7:32:49 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ilovebullets:


Its even greater when nothing like that was said and somebody jumps in to assume. No chest bumping going on. Started off with here is a .270 bullet with highest BC versus a 6.5 bullet with low BC. Then Clarinath and LRRPF52 come in to show that the Accubond BT is a low BC bullet when compared to most 6.5 bullets. Then the numbers are reran and the bullet OP is talking about doesn't look so bad ass after all. Its not the Grendel's fault. I simply said I wouldn't pursue the cartridge because the last thing I wanna do is hunt for impossible to find parts again.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ilovebullets:
Originally Posted By marinesg1012:
Its really great how all these threads turn into "the 6.5 is the best bullet on the planet for all applications"



Its even greater when nothing like that was said and somebody jumps in to assume. No chest bumping going on. Started off with here is a .270 bullet with highest BC versus a 6.5 bullet with low BC. Then Clarinath and LRRPF52 come in to show that the Accubond BT is a low BC bullet when compared to most 6.5 bullets. Then the numbers are reran and the bullet OP is talking about doesn't look so bad ass after all. Its not the Grendel's fault. I simply said I wouldn't pursue the cartridge because the last thing I wanna do is hunt for impossible to find parts again.


I don't agree the 270AR is a hunting round and it swacks the Grendel in the hunting ranges. The Grendel wins at 800yards plus in LRRPF52 comparison where it will never be used for hunting. The 270AR if numbers are correct has what it needs in the ranges it needs it in.
Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1073
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1073
  • Location USA VA, USA
Offline
Link Posted: 7/17/2013 7:55:57 PM EST
[Last Edit: 7/17/2013 8:07:51 PM EST by ilovebullets]
The 270 AR does make good energy numbers but I assume you posted the HITS up on your chart because it is important. If you notice the Grendel and the 270 go below the 500 HITS mark at the same yardage. So I still fail to see the real advantage. At every 100 yard point they are in the same category.

ETA: Either way I like the way the AR platform is going. Experimenting with these different wildcats have created some great cartridges.
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Basic
  • Joined Feb 2013
  • Posts 109
  • Location USA CA, USA
Offline
Basic
  • Joined Feb 2013
  • Posts 109
  • Location USA CA, USA
Offline
Link Posted: 7/17/2013 8:29:52 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By ilovebullets:
The 270 AR does make good energy numbers but I assume you posted the HITS up on your chart because it is important. If you notice the Grendel and the 270 go below the 500 HITS mark at the same yardage. So I still fail to see the real advantage. At every 100 yard point they are in the same category.

ETA: Either way I like the way the AR platform is going. Experimenting with these different wildcats have created some great cartridges.
View Quote


Notice the barrel sizes in the data.
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4490
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4490
  • Location USA UT, USA
Offline
Link Posted: 7/17/2013 9:29:20 PM EST
Harrison said he plans to do a 6.5 version of this cartridge.

The good thing for all of us is that we're basically seeing continuing evolution of the AR15 action to now accommodate loads pushing bullet weights that were traditionally in short-action, manual bolt-action rifles.

The Mauser action went through a series of caliber host evolutions, from 8mm down to 7mm, up to .458, .257, 6.5mm, and every other bore and parent case that would fit in it.

To get competitive performance from the AR15, which is a micro-action, and a self-loader, opens a lot of doors for hunters.

I applaud the progress in this direction, and we're all going to have our pet bore diameters, chamberings, and hopefully multiple preferred options. I see an endless future of caliber arguments into the future, which is a good thing for the AR15 consumer.
Member - 1911 Addict & Grendel Shooter
Avatar
Bronze
  • Joined May 2012
  • Posts 1077
  • Location USA VA, USA
Offline
Bronze
  • Joined May 2012
  • Posts 1077
  • Location USA VA, USA
Offline
Link Posted: 7/17/2013 9:58:23 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By LRRPF52:
Harrison said he plans to do a 6.5 version of this cartridge.

The good thing for all of us is that we're basically seeing continuing evolution of the AR15 action to now accommodate loads pushing bullet weights that were traditionally in short-action, manual bolt-action rifles.

The Mauser action went through a series of caliber host evolutions, from 8mm down to 7mm, up to .458, .257, 6.5mm, and every other bore and parent case that would fit in it.

To get competitive performance from the AR15, which is a micro-action, and a self-loader, opens a lot of doors for hunters.

I applaud the progress in this direction, and we're all going to have our pet bore diameters, chamberings, and hopefully multiple preferred options. I see an endless future of caliber arguments into the future, which is a good thing for the AR15 consumer.
View Quote


I agree. Plus a 270AR necked down to a 6.5 would be bad ass!
"The Constitution shall never be construed to prevent the people of the United States who are peaceable citizens from keeping their own arms."
- Samuel Adams
Basic
  • Joined Jul 2012
  • Posts 81
  • Location USA AZ, USA
Offline
Basic
  • Joined Jul 2012
  • Posts 81
  • Location USA AZ, USA
Offline
Link Posted: 7/18/2013 2:08:09 AM EST
[Last Edit: 7/18/2013 5:47:48 AM EST by SKY-PUP]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By LRRPF52:
Harrison said he plans to do a 6.5 version of this cartridge.

The good thing for all of us is that we're basically seeing continuing evolution of the AR15 action to now accommodate loads pushing bullet weights that were traditionally in short-action, manual bolt-action rifles.

The Mauser action went through a series of caliber host evolutions, from 8mm down to 7mm, up to .458, .257, 6.5mm, and every other bore and parent case that would fit in it.

To get competitive performance from the AR15, which is a micro-action, and a self-loader, opens a lot of doors for hunters.

I applaud the progress in this direction, and we're all going to have our pet bore diameters, chamberings, and hopefully multiple preferred options. I see an endless future of caliber arguments into the future, which is a good thing for the AR15 consumer.
View Quote


Well said. In short: everyone's a winner, no matter their particular caliber preference!

ETA: And, my hat off to those in the industry bold enough to risk breaking the long-established mold.
Member
Avatar
Bronze
  • Joined Oct 2010
  • Posts 5807
  • Location USA WI, USA
Offline
Bronze
  • Joined Oct 2010
  • Posts 5807
  • Location USA WI, USA
Offline
Link Posted: 7/18/2013 9:04:41 AM EST
They really need to stop making these calibers, (270AR necked down to 6.5) I don't make that much money...
Carpe Noctem
A man dies twice. Once when the breath leaves his body and again when the last person who knew him speaks his name for the last time.
Basic
  • Joined Jul 2012
  • Posts 89
  • Location USA AZ, USA
Offline
Basic
  • Joined Jul 2012
  • Posts 89
  • Location USA AZ, USA
Offline
Link Posted: 8/18/2013 8:36:24 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By LRRPF52:
Harrison said he plans to do a 6.5 version of this cartridge.
View Quote


Any performance data on the planned 6.5/270AR SPR, yet? Such a 21st Century cartridge designed for a 21st Century Big Bolt AR-15 platform may just be my cup of tea!
Basic
  • Joined Jun 2007
  • Posts 3062
  • Location USA TN, USA
Online
Basic
  • Joined Jun 2007
  • Posts 3062
  • Location USA TN, USA
Online
Link Posted: 8/19/2013 4:23:10 AM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tumbleweed:


Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps
Basic
  • Joined Apr 2013
  • Posts 6
  • Location USA TX, USA
Offline
Basic
  • Joined Apr 2013
  • Posts 6
  • Location USA TX, USA
Offline
Link Posted: 8/19/2013 12:12:27 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By molar:


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By molar:
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps


Pretty sure you just duplicated the WSSM series of cartridges with that idea.
Basic
  • Joined Jun 2007
  • Posts 3063
  • Location USA TN, USA
Online
Basic
  • Joined Jun 2007
  • Posts 3063
  • Location USA TN, USA
Online
Link Posted: 8/19/2013 12:29:01 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By centurion20000:


Pretty sure you just duplicated the WSSM series of cartridges with that idea.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By centurion20000:
Originally Posted By molar:
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps


Pretty sure you just duplicated the WSSM series of cartridges with that idea.


AFAIK, the 458 Socom and WSSM series do not use the same parent case. In fact, they have no parent cases. They are their own deal.

I'm also pretty sure you have to use special mags by DTech with the WSSM's. The Socom wildcat would use standard mags and you could use a 458 Socom bolt.
Extension Twister :/
Avatar
Platinum
  • Joined Jun 2008
  • Posts 1131
  • Location USA LA, USA
Offline
Platinum
  • Joined Jun 2008
  • Posts 1131
  • Location USA LA, USA
Offline
Link Posted: 8/19/2013 1:17:44 PM EST
[Last Edit: 8/19/2013 1:31:37 PM EST by 762x40mm]
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By molar:

AFAIK, the 458 Socom and WSSM series do not use the same parent case. In fact, they have no parent cases. They are their own deal.

I'm also pretty sure you have to use special mags by DTech with the WSSM's. The Socom wildcat would use standard mags and you could use a 458 Socom bolt.
View Quote



11.2x72 Schuler and 425 Westley Richards seems.......familiar......



" The only way I got to keep them Tigers busy is to let them shoot holes in me..."

" tore away the bottom and saw life is a test "
Getnlwr is my hero
Avatar
Lifetime Member
  • Joined Jan 2003
  • Posts 3675
  • Location USA WA, USA
Offline
Lifetime Member
  • Joined Jan 2003
  • Posts 3675
  • Location USA WA, USA
Offline
Link Posted: 8/19/2013 1:53:02 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By molar:


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By molar:
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps

If you can do it with low pressure then fine, but old tinstaafl (there is no such thing as a free lunch) rears its ugly head. The AR-15 is a short COAL and a small bolt lug design. Both of these will bite you. A 458 SOCOM necked down to 6.5mm will suffer from two things:

The LR 6.5mm bullet is very long and will seriously impact powder capacity. A rough calculation tells me that a Sierra 142gr MK will be protruding 0.3" past the shoulder and into the case when seated at max COAL. That is like 30% of the powder column, though the case is so fat you're probably only losing 15-20% powder capacity. Now given a max capacity for powder, you are forced to choose a burn rate that will give you the best performance.

Unfortunately cases of this type (big fat fuckers) in an AR-15 require a low pressure load to keep bolt thrust from 'sploding your lugs. So, loaded at .44mag pressures (or less), the 6.5x458 chambered in an AR-15 is so neutered the question becomes "just why".

I'm all for a nice little 6.5 that tickles the performance of a .264 Win Mag but not quite that much. Barrel life is something I'd favor but the capability would be cool. To get there I think it is best to adapt from an AR-10 platform, where you have the case length and a much larger margin to design a barrel extension that can handle a mag rifle load.
The only fool bigger than the person who knows it all is the person who argues with him. Stanislaw Jerszy Lec
fuego antipático
Extension Twister :/
Avatar
Platinum
  • Joined Jun 2008
  • Posts 1132
  • Location USA LA, USA
Offline
Platinum
  • Joined Jun 2008
  • Posts 1132
  • Location USA LA, USA
Offline
Link Posted: 8/19/2013 2:14:28 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tumbleweed:

If you can do it with low pressure then fine, but old tinstaafl (there is no such thing as a free lunch) rears its ugly head. The AR-15 is a short COAL and a small bolt lug design. Both of these will bite you. A 458 SOCOM necked down to 6.5mm will suffer from two things:

The LR 6.5mm bullet is very long and will seriously impact powder capacity. A rough calculation tells me that a Sierra 142gr MK will be protruding 0.3" past the shoulder and into the case when seated at max COAL. That is like 30% of the powder column, though the case is so fat you're probably only losing 15-20% powder capacity. Now given a max capacity for powder, you are forced to choose a burn rate that will give you the best performance.

Unfortunately cases of this type (big fat fuckers) in an AR-15 require a low pressure load to keep bolt thrust from 'sploding your lugs. So, loaded at .44mag pressures (or less), the 6.5x458 chambered in an AR-15 is so neutered the question becomes "just why".

I'm all for a nice little 6.5 that tickles the performance of a .264 Win Mag but not quite that much. Barrel life is something I'd favor but the capability would be cool. To get there I think it is best to adapt from an AR-10 platform, where you have the case length and a much larger margin to design a barrel extension that can handle a mag rifle load.
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By tumbleweed:
Originally Posted By molar:
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps

If you can do it with low pressure then fine, but old tinstaafl (there is no such thing as a free lunch) rears its ugly head. The AR-15 is a short COAL and a small bolt lug design. Both of these will bite you. A 458 SOCOM necked down to 6.5mm will suffer from two things:

The LR 6.5mm bullet is very long and will seriously impact powder capacity. A rough calculation tells me that a Sierra 142gr MK will be protruding 0.3" past the shoulder and into the case when seated at max COAL. That is like 30% of the powder column, though the case is so fat you're probably only losing 15-20% powder capacity. Now given a max capacity for powder, you are forced to choose a burn rate that will give you the best performance.

Unfortunately cases of this type (big fat fuckers) in an AR-15 require a low pressure load to keep bolt thrust from 'sploding your lugs. So, loaded at .44mag pressures (or less), the 6.5x458 chambered in an AR-15 is so neutered the question becomes "just why".

I'm all for a nice little 6.5 that tickles the performance of a .264 Win Mag but not quite that much. Barrel life is something I'd favor but the capability would be cool. To get there I think it is best to adapt from an AR-10 platform, where you have the case length and a much larger margin to design a barrel extension that can handle a mag rifle load.


Excellent points....and also to add: one of the areas expected to 'grow' at the moment of firing is the shoulder area....as it increases to chamber diameter and the the face of the shoulder tries to grow forward to take up any excess headspace and push off the front of the chamber......as you decrease the caliber you also increase the surface area of the front of the cartridge and increase its mechanical advantage to push rearward.....that combined with a rebated rim ain't a real ideal combination.....in my opinion we're using rebated rims the complete opposite forwhich they were designed....just out of necessity to follow the AR bolt pattern rather than a bolt that telescopes into the chamber....
" The only way I got to keep them Tigers busy is to let them shoot holes in me..."

" tore away the bottom and saw life is a test "
Basic
  • Joined Jun 2007
  • Posts 3064
  • Location USA TN, USA
Online
Basic
  • Joined Jun 2007
  • Posts 3064
  • Location USA TN, USA
Online
Link Posted: 8/19/2013 2:52:34 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 762x40mm:


Excellent points....and also to add: one of the areas expected to 'grow' at the moment of firing is the shoulder area....as it increases to chamber diameter and the the face of the shoulder tries to grow forward to take up any excess headspace and push off the front of the chamber......as you decrease the caliber you also increase the surface area of the front of the cartridge and increase its mechanical advantage to push rearward.....that combined with a rebated rim ain't a real ideal combination.....in my opinion we're using rebated rims the complete opposite forwhich they were designed....just out of necessity to follow the AR bolt pattern rather than a bolt that telescopes into the chamber....
View Quote View All Quotes
View All Quotes
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By 762x40mm:
Originally Posted By tumbleweed:
Originally Posted By molar:
Originally Posted By tumbleweed:

Originally Posted By LRRPF52:
I have yet to witness the performance 1st-hand, so color me equally skeptical, aside from the fact that the case will only single-stack in the AR15 frame. I'll get a hold of the guys working on it and confirm that I heard correctly.

Longing for .264 Win Mag performance in an AR-15 is a bit misplaced in my opinion.


I've long wondered what kind of performance can be had by necking down a 458 Socom or 450 Bushmaster to 6.5 or 7mm?

If you can push a 350 gr bullet in the low 2000 fps range with a 458 Socom, I imagine you could push a 130 gr 6.5 past 3000 fps

If you can do it with low pressure then fine, but old tinstaafl (there is no such thing as a free lunch) rears its ugly head. The AR-15 is a short COAL and a small bolt lug design. Both of these will bite you. A 458 SOCOM necked down to 6.5mm will suffer from two things:

The LR 6.5mm bullet is very long and will seriously impact powder capacity. A rough calculation tells me that a Sierra 142gr MK will be protruding 0.3" past the shoulder and into the case when seated at max COAL. That is like 30% of the powder column, though the case is so fat you're probably only losing 15-20% powder capacity. Now given a max capacity for powder, you are forced to choose a burn rate that will give you the best performance.

Unfortunately cases of this type (big fat fuckers) in an AR-15 require a low pressure load to keep bolt thrust from 'sploding your lugs. So, loaded at .44mag pressures (or less), the 6.5x458 chambered in an AR-15 is so neutered the question becomes "just why".

I'm all for a nice little 6.5 that tickles the performance of a .264 Win Mag but not quite that much. Barrel life is something I'd favor but the capability would be cool. To get there I think it is best to adapt from an AR-10 platform, where you have the case length and a much larger margin to design a barrel extension that can handle a mag rifle load.


Excellent points....and also to add: one of the areas expected to 'grow' at the moment of firing is the shoulder area....as it increases to chamber diameter and the the face of the shoulder tries to grow forward to take up any excess headspace and push off the front of the chamber......as you decrease the caliber you also increase the surface area of the front of the cartridge and increase its mechanical advantage to push rearward.....that combined with a rebated rim ain't a real ideal combination.....in my opinion we're using rebated rims the complete opposite forwhich they were designed....just out of necessity to follow the AR bolt pattern rather than a bolt that telescopes into the chamber....


Ok that makes sense. What about a 375 Socom or 338 Socom?
Basic
  • Joined Nov 2000
  • Posts 12659
  • Location USA CA, USA
Offline
Basic
  • Joined Nov 2000
  • Posts 12659
  • Location USA CA, USA
Offline
Link Posted: 8/19/2013 3:05:51 PM EST
Yeah...

With having an ar10 90% of these problems are self alieviating.

Now if i wanted a long distance round i might as well throw down on the ar10 platform rather than the ar15 platform.

For ar15 i would likely go 6.5 grendel and be done with it. All the known issues regarding bolt wear/failure, mag issues, loads, no needing to fireform/wildcat brass, just isnt worth it.
Extension Twister :/
Avatar
Platinum
  • Joined Jun 2008
  • Posts 1134
  • Location USA LA, USA
Offline
Platinum
  • Joined Jun 2008
  • Posts 1134
  • Location USA LA, USA
Offline
Link Posted: 8/19/2013 3:16:03 PM EST
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By uglygun:
Yeah...

With having an ar10 90% of these problems are self alieviating.

Now if i wanted a long distance round i might as well throw down on the ar10 platform rather than the ar15 platform.

For ar15 i would likely go 6.5 grendel and be done with it. All the known issues regarding bolt wear/failure, mag issues, loads, no needing to fireform/wildcat brass, just isnt worth it.
View Quote



Yep....a 10 in 260 or 6.5 CM for the win....



" The only way I got to keep them Tigers busy is to let them shoot holes in me..."

" tore away the bottom and saw life is a test "
Basic
  • Joined Sep 2007
  • Posts 1266
  • Location USA FL, USA
Offline
Basic
  • Joined Sep 2007
  • Posts 1266
  • Location USA FL, USA
Offline
Link Posted: 8/19/2013 5:04:43 PM EST
They need to build one in 338.
Member
Avatar
Bronze
  • Joined Oct 2011
  • Posts 4723
  • Location USA UT, USA
Offline
Bronze
  • Joined Oct 2011
  • Posts 4723
  • Location USA UT, USA
Offline
Link Posted: 8/19/2013 8:00:06 PM EST
I think the success of any high case capacity, high pressure hunting rifles built for compatibility with at least the AR15 lower receiver will need several things:

* The bolt face and lugs need to be at least the size of the AR10 bolt.
* The barrel extension needs to be the size of an AR10
* The upper needs to accommodate the larger extension, and provide enough material support.

As you look at these factors, you start to ask if it isn't prudent to just start with a new set of receivers entirely, and we've hashed over the AR12.5 idea for some years now.

When I see Oly Arms doing things like shaving backwards into the magwell of the AR15 to fit .22-250 into it with their own mag, and practically everyone who shoots a wildcat or even .223 Wylde wishing for more COL, I guess we have to see when the market demand threshold will tip in favor of the "AR12.5" action, if ever.

I can see it eventually becoming a reality if enough demand is generated from:

* Hunters who are used to the AR15, but want short-action performance without going to an AR10
* Long-range shooters
* Hi-power shooters
* Wild-catters looking for more usable COAL

One thing that could defer this possibility would be an AR10 with economical approaches to significantly reducing weight, other than carbon fiber wrapped barrels. Recent developments in the AR15 market might be paving the way for that to happen, but many of us still like the compact AR15 frame. I think the legal environment is a bigger factor than anything though.
Basic
  • Joined May 2007
  • Posts 720
  • Location USA USA
Offline
Basic
  • Joined May 2007
  • Posts 720
  • Location USA USA
Offline
Link Posted: 8/20/2013 10:34:42 AM EST
Isn't this based on a shortened 308 case?


Isn't that very different from reducing a 458 case as the rim is much larger.

Also his bolts for the 270AR are much larger (super bolt I think) which would help with the increase in pressure.


I would love to see one of these in a micro action and 60* bolt throw
Top