AR15.Com Archives
 6.8 Variant, The 25 DTI
ricky_arthur  [Member]
2/28/2012 1:06:36 PM
I went through a few pages and did a search and didn't find any discussion about Dtech's Line of 6.8 wildcats called the DTI. (Dtech Improved)

The 22 DTI
6mm DTI,
6.5 DTI
and 25 DTI.

A 6.8 case necked down and shoulder blown out to increase case capacity.

I have a 25 DTI scheduled for delivery on Friday, so I will be sure and post a range report. Any one hear about them or shoot one of the DTI Line?

I'm planning on 75gr sierras for coyotes, and an 80 gr Barnes for deer. Velocities should be 3200 and 3000 respectively. Should be a fun round.

Some sized Brass,
ricky_arthur  [Member]
2/28/2012 11:33:20 PM
Never mind I guess. I though there would be some interest, but I won't bother with a RR.
Direct-Drive  [Member]
2/29/2012 12:07:38 AM
Originally Posted By ricky_arthur:
Never mind I guess. I though there would be some interest, but I won't bother with a RR.

DTech does some great work.
Looking forward to the range report.

Why did you choose .25 over 6mm ?

I like 6mm Rem and .25-06 so I'm not prejudiced, just curious.
GGGBeo50  [Member]
2/29/2012 12:21:47 AM
Originally Posted By ricky_arthur:
Never mind I guess. I though there would be some interest, but I won't bother with a RR.


you didnt give people much time to respond. people who have time to comment about variants like this are usually doing productive things of their own. I just got done resizing about 200 peices of 6mm WOA brass. Since I found a moment to surf after pouring a glass of makers mark and water, i figured i would chime in. I would like to see results of this 25 cal variant. We know the 6.8 spc parent case has a lot of opportunity in several areas for variant bores because of its adaptability to ar-15s. I know that testing done with this parent case wasnt that extensive considering the budget and trouble with chamber designs along the way. I like the 6.8spc, it has its place, but it like the parent case more. Example; I took a look at the 30HRT real hard before I bought a 300 aac BLK....while also supporting the suppressed usage argument, give me a second to explain. Im all about vesatility when it comes to consumables:

1. I shoot a 223. therefore I have .223 brass. therefore its on every street corner. This means I can make 6x45 brass and 300 blk brass with my dies and trimmers. cheap dude.
2. I use h335 powder for my 223 loads. I can also use H335 for my 6x45 loads as well as my 308 winchester loads and my 6.8 spc loads. that means i can buy big boy cans and not sweat.
3. I have an ar-10 in 308 winchester. I can use the projectiles for my 300 blk.
4. My 6.8 spc is a brat because it requires 2 major components dissimilar over the latter calibers that have 2 similar components amongst themselves. So, If I can adapt the 6.8 spc parent case to a 6mm, I benefit in a way while still going out on a limb because i have 6mm projectiles for my 6x45 to utilize.

So thats my drift. In favor of your variant, how do the 25 cal projectiles perform in terms of BC against the 270? I havent given it any thought or research. I know that a 6mm 90g FMJBT moving 3000 fps from a 20" barrel carries enough energy and terminal performance after 250 yards to pull the rug out from underneath a 6.8 any day of the week. Good to have if you need a stretch. I also know that a 6mm 90g FMJBT moving 2850 fps from a 16-18" barrel flies the same path as a 62g M855 from a 20" 5.56 becoming attractive to those utilizing optics with ballistic recticles calibrated for NATO ammunition (Trijicon ACOG). Something to consider...

So yes, keep us informed on your 25 cal solution. I think its cool and if you talk about it enough, I may find a barrel/bolt combo handed to me by a man in a brown uniform with a plastic tipped pen and a green letter digital clipboard. cheers.

cool links:

http://www.dtic.mil/ndia/2009infantrysmallarms/tuesdaysessioniii8524.pdf

http://www.dtic.mil/ndia/2008Intl/Roberts.pdf
ricky_arthur  [Member]
2/29/2012 10:19:21 PM



DTech does some great work.
Looking forward to the range report.

Why did you choose .25 over 6mm ?

I like 6mm Rem and .25-06 so I'm not prejudiced, just curious.



The reason for the .25 over the 6mm is that quick load predicted that the .25 DTI would have 95-99% Powder burn (depending on powder) in an 18 inch BBL. The 6mm needs a 22 inch BBL to get the same powder Burn percentages. Since I already have a couple 6.8's and lots of brass handy, the DTI wildcats made sense, but I wanted one for coyote calling in a light weight short BBL build, so the 22" 6mm DTI didn't really fit that bill.


I'm really more than a little surprised that ARF.com is not up to date and talking about these 6.8 wildcats. A much smaller predator website has been abuzz about them since they were introduced last year. I know of about half dozen people who already have one and reports are very good. I'll go ahead and post some pics on Friday when I get it, just in case anyone is interested.

Ricky
Direct-Drive  [Member]
2/29/2012 10:29:42 PM
Thanks for that.
Looking forward to the field reports.


I might have to go over to PredatorMasters more often.
Per capita, probably not many wildcatters here.
GGGBeo50  [Member]
2/29/2012 11:56:54 PM
Originally Posted By ricky_arthur:



DTech does some great work.
Looking forward to the range report.

Why did you choose .25 over 6mm ?

I like 6mm Rem and .25-06 so I'm not prejudiced, just curious.



The reason for the .25 over the 6mm is that quick load predicted that the .25 DTI would have 95-99% Powder burn (depending on powder) in an 18 inch BBL. The 6mm needs a 22 inch BBL to get the same powder Burn percentages. Since I already have a couple 6.8's and lots of brass handy, the DTI wildcats made sense, but I wanted one for coyote calling in a light weight short BBL build, so the 22" 6mm DTI didn't really fit that bill.


This is something I have heard a few times. I dont have access to quick load but I talked to a guy at either DTI or WOA that informed about anything shorter than a 20" becoming a "grass burner". We tried a few different scenarios because I was wanting a lightweight 16"-18" rig that keep decent velocities up and we ran into the powder burn issues. I guess my question next is:

Yes the powder may not all burn in that configuration; How does that compare to a 16" 308 and a 24" 308? Does a 16" ar-10 get 95-99percent powder burn? My original goal was to have a lightweight and shorter6mm WOA AR-15 that could outperform or match the velocities of my 20" 6x45. I figured since I couldnt get any more case capacity out of my 6x45, I was having to set the bullets futher and add more powder out to achieve higher velocities. The 6.8 parent case seemed to be the answer because of the greater volume. Thoughts?
ricky_arthur  [Member]
3/1/2012 9:47:34 AM
There is certainly no reason you couldn't go with an 18 or 20 inch 6mm DTI. Not having 100% powder burn is not the end of the world. A 16 308 is no where near 100 percent powder burn and probably gives up 200-300+ FPS as a result. Sometimes the shorter, lighter BBL is worth losing some performance.

I went with the 25 DTI because I can get all the performance possible from the round in the shorter BBL. I ran some numbers on the 80 gr Barnes TTSX and with a minimum velocity of 1800FPS (for reliable expansion), If I can get 3000 FPS in a safe load (very likely) that bullet will still be north of 1800 FPS till somewhere around 450 Yards. That was pretty impressive to me.
Siringo  [Member]
3/2/2012 10:44:49 AM
I had tried the 80 grain Barnes in the 25 DTI (I have an 18 inch barrel) and could not get over 2900 fps with the bullet –– and that was over max pressure. Safe pressure/velocities were in the neighborhood of 2800 fps +. This is a very long bullet for its weight and eats up powder space. In fact, it seating depth into the case is the same as all the 100 grain sierra's. It is not a useful bullet for this cartridge. Maybe with a 22 inch you can get closer to the magic 3000 that you want, but it will be HOT!

For those of you that are using Quick Load, pay attention to your case capacity. If you are using Hornady brass, they hold less water than the SSA cases. For instance, MY SSA cases hold an average of 35.7 grains of H2O. The Hornadys are 34.5 grains. The quick-load program I had originally said 37.9 grains. That is a huge difference and will lead you into trouble. Just check the cases you have and adjust the program parameter accordingly.

One more thing –––– sized, but unfired SSA cases hold 0.7 grains less H2O than the fired cases. So when you are fire forming, reduce you charges!

I am really only interested in 100 grain bullets with the 25 DTI. My goal was to duplicate velocities of the 250-3000 Savage cartridge, which I can do ––- but with an 18 inch barrel instead of a 26 inch as in the savage. This is an accurate cartridge, primarily designed for lighter weight 25 caliber bullets for predator/varmint hunting.
ricky_arthur  [Member]
3/3/2012 12:09:05 AM
Woke up this morning at 6 to go running (training for a marathon) Walked out the door to blizzard conditions, 25+ MPH winds, snow and temps in the teens. Ran 8 miles and nearly froze important and sensitive parts of my anatomy off.

I kept thinking. "I don't mind this for my run as long as it tapers off this afternoon so I can go to the range".

The UPS truck hits town at 12:00 and I left work to catch them as they unload. Drat! Storm had delayed the truck by an hour.

I left work again an hour later and stood in the Icy Wind watching till I saw the correct size package exit the truck.

"That's Mine", I yelled to the driver and he handed it to me. (they know me well):)

I ran back to work and took the time to open the box on my desk.



Then back to work, looking out the door at the trees every 15 minutes hoping to see a calming of the wind. Finally time for shift change so I ran home and put things together.





I watched all evening hoping the wind would back off enough to at least go sight her in, but no Luck, This is obviously the long way around for saying, The Range report will have to wait until tomorrow.

Think I'll go clean it since that's about all I can do tonight. :(
QuicksilverJPR  [Team Member]
3/3/2012 12:14:45 AM
Looks a lot like my 6.8 (don't have nearly as fancy a barrel as you, however). Same stock, lower, etc....
LRRPF52  [Team Member]
3/3/2012 1:12:17 PM
Any chance you can run the 115gr VLD's from AR15 mag length? The .25-06 can run the 115's over 3000fps. If you could do that out of an AR15, it would be another nail in the coffin for the Mauser action moving into the 21st Century, as much as I love my Mauser action Pre-64 Winchester.
ricky_arthur  [Member]
3/3/2012 5:22:43 PM
Originally Posted By LRRPF52:
Any chance you can run the 115gr VLD's from AR15 mag length? The .25-06 can run the 115's over 3000fps. If you could do that out of an AR15, it would be another nail in the coffin for the Mauser action moving into the 21st Century, as much as I love my Mauser action Pre-64 Winchester.


No, even the 100gr bullets are anemic because of Mag length restrictions. This 25 DTI is designed for 70-90 gr Bullets.

Winds calmed down to a breeze today so I slogged through the Mud to the range. I forgot my good camera and was stuck with cell phone pics.

I had 9 3 round Loads with Ramshot Exterminator and 75 gr sierra bullets. Starting at 27.5 up to Max load of 31.4.

And 3 3 round loads with the Barnes 80 gr TTSX and Reloader 10X.
27.0. 27.5 and 28.0

3 shots to sight In and then I ran the rest through the Chrony.

These were mainly to fire form brass, break in the BBL and get a feel for pressure on loads.

Velocities were less than I expected for the 75gr sierras.

30.5 was the best 3 shot group with velocities averaging 2925 FPS.


The good news was that 31.0 and 31.4(max Load) were both about 3/4 also, suggesting a fairly wide accuracy node.


Velocities at 31.4gr exterminator averaged 3015. Over 200 FPS slower than predicted by quick Load. Not sure why. Temperature could be an issue as it was barely above freezing.

Primers still looked good, and there is probably a little more room above 31.4 as I saw No signs of High Pressure.

Next I tried the 80 gr Barnes TTSX and Reloader 10X.

All 3 groups were about an inch.

Pictured are the 27.0 and 28.0 as the bottom 2 3 shot groups here. The Center group was fired by a friend of mine who called the shot pulled low and blamed it on the cold.



I actually got a little better velocity than I expected with these, with the 28.0 gr Reloader 10X I got an average of 2880 FPS but showed mild pressure signs so 2900 is probably the top end here, Just as Mike suggested.

Just a couple notes, BBl clean up was easy for a new BBL 4-5 patches with sweets 7.62 and then white patches would appear.

Also function was 100% with no Failures of any Kind.

Max Cartridge length with the PRI magazines is about 2.280.

I will post more when I get back out to the range, tomorrow or Monday.

LRRPF52  [Team Member]
3/3/2012 9:11:51 PM
Have you looked at Optimum Barrel Time to tighten up your loads? QL has the feature on it.

Basically, you're timing the exit of the projectile with the shock wave resonating through the barrel as far from the muzzle as possible.

You just need to look at the Optimum Barrel Times for your barrel length, reference them with your pressure limitations, and load within those accuracy nodes.

Using Quick Load and OBT
chris65  [Team Member]
3/4/2012 1:22:18 PM
Agreed, sounds like a fun, interesting caliber.

Tell us more about case prep...

Do the cases lengthen when necked-down?

If yes, what is a 10-case average length after resizing?

Are they then trimmed-back to original length to fit the intended (70-90gr) bullets?

Barrel twist?
ricky_arthur  [Member]
3/4/2012 5:54:53 PM
Originally Posted By chris65:
Agreed, sounds like a fun, interesting caliber.

Tell us more about case prep...

Do the cases lengthen when necked-down?

If yes, what is a 10-case average length after resizing?

Are they then trimmed-back to original length to fit the intended (70-90gr) bullets?

Barrel twist?


Case prep is as simple as running 6.8 Brass into the custom hornady 25 DTI sizing Dies and then loading. The shoulder is blown out just a little to 30deg the first time they are fired.

I measured 10 new sized cases after resizing and all were Between 1.678 and 1.681. Trim to length is 1.676 I would say that no, the case does NOT noticeably lengthen when resizing. At least not enough to need to trim.

BBl twist is 1-10


alphawingnut  [Team Member]
3/4/2012 6:24:23 PM
what does the loaded cartridge look like, especially compared to a normal 6.8
ricky_arthur  [Member]
3/4/2012 7:56:25 PM
Another trip to the Range today, accompanied by My daughter.

Want a little contrast?

Here she is Last night Just before her Junior Prom.



And here, with me at the range today. I'm proud of her to say the least.



Back to the 25 DTI

I tried reloader 10X and 3 bullets today. 75 Gr sierra, 75 Gr Vmax and 80gr Barnes TTSX. Overall, velocities were better, but accuracy not as consistent.

Temps and conditions were warm (45 degrees) and the winds calm.

The last group I shot was the Barnes 80 Gr TTSX and 28.5 gr reloader 10X. I worked up to 28.0 gr yesterday, and wanted to try up to 28.5. It was good news bad news. The first and second shot at 28.5 went into the same hole, the second just outside, for a decent group, and an average velocity of (Gasp) 3050FPS, The bad news was it is hot, hot! Ejector swipe and flat primers. I wouldn't dare shoot it in summer temps.

80gr TTSX group. Center of target.


Groups overall were not as good with Rl 10X as they were with Xterminator, but both 75gr Bullets had one decent group.

The 75gr Vmax at 29.6 RL 10X (max load and nearly as hot as the Barnes load) is pictured above with the TTSX group on the bottom right. Velocity average was. 3130 FPS

the 75 gr sierra load at 29.0hr RL 10X is here and averaged 3070FPS



Time to try a few 5 shot groups to see what it can do.
QuicksilverJPR  [Team Member]
3/5/2012 10:52:27 AM
Originally Posted By ricky_arthur:
Another trip to the Range today, accompanied by My daughter.

Want a little contrast?

Here she is Last night Just before her Junior Prom.

http://i856.photobucket.com/albums/ab121/ricky_arthur/IMAG0646.jpg

And here, with me at the range today. I'm proud of her to say the least.

http://i856.photobucket.com/albums/ab121/ricky_arthur/IMAG0650.jpg

Back to the 25 DTI

I tried reloader 10X and 3 bullets today. 75 Gr sierra, 75 Gr Vmax and 80gr Barnes TTSX. Overall, velocities were better, but accuracy not as consistent.

Temps and conditions were warm (45 degrees) and the winds calm.

The last group I shot was the Barnes 80 Gr TTSX and 28.5 gr reloader 10X. I worked up to 28.0 gr yesterday, and wanted to try up to 28.5. It was good news bad news. The first and second shot at 28.5 went into the same hole, the second just outside, for a decent group, and an average velocity of (Gasp) 3050FPS, The bad news was it is hot, hot! Ejector swipe and flat primers. I wouldn't dare shoot it in summer temps.

80gr TTSX group. Center of target.
http://i856.photobucket.com/albums/ab121/ricky_arthur/IMAG0653.jpg

Groups overall were not as good with Rl 10X as they were with Xterminator, but both 75gr Bullets had one decent group.

The 75gr Vmax at 29.6 RL 10X (max load and nearly as hot as the Barnes load) is pictured above with the TTSX group on the bottom right. Velocity average was. 3130 FPS

the 75 gr sierra load at 29.0hr RL 10X is here and averaged 3070FPS

http://i856.photobucket.com/albums/ab121/ricky_arthur/IMAG0654.jpg

Time to try a few 5 shot groups to see what it can do.


I'm looking forward to my girls going out and having a good time (they're almost 6 and 3 now), just not the boys that will undoubtedly be going with them....

But that's what the guns are for!

Nice grouping. I like .257 caliber guns. Always have....

Siringo  [Member]
3/5/2012 6:03:10 PM
Ricky –––– were did you get your quick load data from????
hi-tech-rancher  [Team Member]
3/5/2012 7:54:37 PM
Thanks for the RR. I see where you are going with this, but I doubt you will get much faster than 6.8 loads of equal weight (if only we had 75 grain .277's!) . With an 80 grain GS HV, I am getting 3250, but those bullets are really hard to find. .25's are much easier. I sure wish Hornady made the VMax in 75 grains for the 6.8.

As for the Barnes TTSX in 80 grains, you have three things with which to contend. 1) the bullets are long for that case, and will limit capacity, even with PRI mags, which allow 2.30" OAL.

2) the bore area to case size ratio is obviously a little higher with .277 than .25, so that is why 6.8 is so incredibly efficient. Drop down in caliber, and that goes down a little. and 3) Re 10X, while a great place to start, is probably being compressed at 28 grains and up.

You might try AA2200 to see if a ball powder does not give lower pressure at 100-105% case fill, and higher velocity. Its a double based, advanced ball that is designed for higher velocity and lower pressure, with a burn rate very near Re10X.
Siringo  [Member]
3/5/2012 9:44:01 PM
The smaller bore likes slower powders than normal for the 6.8. I tried 2200 and it is too fast for the 25. Although my trials where only with 100's. TAC gave great accuracy and WW748 gave gave better velocity than TAC. BUT I could not get over 2700 fps. While 2200 is a magic powder for the 6.8, I decided to try LeverEvolution powder in hopes of getting more velocity with the 100 grain projectiles. I might have posted this before, but I figured if it was OK to load in the 25-35 Winchester, lets see what it will do in the 25 (essentially the same case). Lo and behold, I got 2830 fps out of a 100 gr. Sierra boat-tail softpoint. I have no data to go from other than fly by the seat of my pants. The SSA cases with the 100 gr. Sierra BTGK held 32.2 grains of leverevolution. I dropped down to 25 grains and worked my way up to 32. 32 grains will consistently group under1 inch at a 100 yards.

I was up at the range this weekend shooting the 90 grain game king with leverevolution to fire form about 100 cases. Accuracy at 100 yards was at the 1 inch mark to 1 3/8 for 10 shots each. A few groups were under 1 inch. These were 10 shot groups shot quickly and my rest was not the best. I had forgotten my chrono. I hope to be able to push these to 3000 fps.

One thing tho –––– the powder is dirty. 10X is dirty too,

I have fired about 1000 rounds since I got this upper from Dtech. I am amazed at the consistency of the barrel. For instance, when testing the LE Powder, firing at 100 yards off a bench, starting at 25 grains (2103 fps) and stopping at 32 grains (2830), my group size was 1 1/4 inches wide by 2 inches tall. That is over 700 fps variation in velocity. So much for SD and ES –– EH!
ricky_arthur  [Member]
3/5/2012 9:48:35 PM
Originally Posted By Siringo:
Ricky –––– were did you get your quick load data from????



I got the data from Mike Mili at Dtech, with the exception of the 80gr TTSX and with that I just started low and worked up.
ricky_arthur  [Member]
3/6/2012 10:06:20 AM
Forecast calls for high winds later today so I snuck out to the range at dawn while it was still dead calm. I noticed some POI shifts during the last 2 range sessions, so I pulled the Vortex Viper scope off and replaced it with a Burris signature 6-24 X 50 scope that has proven reliable just to make sure I didn't have a scope problem.

I only took 2 loads, 3 of the best load for the Sierra 75gr which is 31.4 Xterminator and also 5 rounds of the 75gr vmax with 29.5 RL 10X.

I still do not see anywhere near the velocity That the load data I have says I should be getting with the 75gr Sierra. This Load is right at 3000FPS while the load Data shows it at 3200+. Does anyone else have Chrono data on this bullet?

Anyway, it put the 3 shots this morning into under 1/2 Inch so I will load up some 5 shot groups to verify. Very happy with the accuracy there, but I suspect the load Data is Off.

It is the top right group in this pic


The 75gr Vmax load is the same load that Yesturday I put 4 shots into 3/4 inch but the 5th shot was a flyer that opened up the group to 1 1/4. Not too Bad even with the flyer, so I shot it again this morning.

This time I got 4 shots into Less than .4 inch But the 5 shot group still had a flyer, this time it was shot number 2. shots 1,3,4 and 5 were under 1/2 inch. The group opened up to just over an inch with the Flyer.


I am confident I did not pull the shot, so this type of thing drives me crazy.
Still, I like the accuracy and The velocity with this combo is just over 3100 FPS, so I will load a few up to use today when I go calling.
Siringo  [Member]
3/6/2012 10:27:06 AM
I suspect that the loads were developed with a 22 inch barrel. Since you have an 18 inch, you can expect a drop in velocity. I had the same scenario. Using my Quick load program and your charges, the predicted velocity for the 10X charge is 3078 fps and for the Xterm charge is 3062 fps. These numbers are using an 18 inch barrel. Changing the barrel length to 22 inches bumps the velocity to 3200 fps. Your accuracy looks very good.
ricky_arthur  [Member]
3/6/2012 11:05:54 AM
Originally Posted By Siringo:
I suspect that the loads were developed with a 22 inch barrel. Since you have an 18 inch, you can expect a drop in velocity. I had the same scenario. Using my Quick load program and your charges, the predicted velocity for the 10X charge is 3078 fps and for the Xterm charge is 3062 fps. These numbers are using an 18 inch barrel. Changing the barrel length to 22 inches bumps the velocity to 3200 fps. Your accuracy looks very good.


Thanks, Siringo, The load data I have From Mike for the 75gr Sierra Specifically states that it is for an 18 inch BBL. I suspect that the data is wrong (at least the BBL length info part), it also shows 98.55 % powder burn in an 18 inch BBl and if that is the case, a 22 inch BBl is unlikely to net an additional 200 FPS. I suspected something was amiss when I looked at it because I could see no reason why the 75 gr Vmax would run 200 FPS slower than the 75gr sierra. I think the velocity Data for the 75gr Vmax is probably correct. However, If this is the case it may put a kink in the 25DTI vs the 6mm DTI discussion, as the main argument for the 25 is efficiency in an 18 inch BBL.

Siringo  [Member]
3/6/2012 1:40:48 PM


This is a cartridge board that I put together showing the overall cartridge lengths versus bullet weight. These were just the bullets that I had tried.
Siringo  [Member]
3/6/2012 1:42:48 PM
That didn't work.
BIGGDAWG  [Team Member]
3/6/2012 1:52:07 PM
fixed it for ya


Siringo  [Member]
3/6/2012 1:52:16 PM


Here are some of the examples of what I was working with.

Also, the 75 grain Sierra is .757 inches long and the 75 grain VMax is .875 inches long. Big difference. Just look a the difference in the 100 grain Nosler versus the 100 grain Sierras. The Nosler was 100 fps slower ––- because of increase bore surface contact. What are the OAL cartridge lengths you are using for the 75"??

Also, the Burn Rate is not a good indicator of velocity by itself. For instance, a particular powder may have a 100% burn rate in an 18" barrel, but that does not mean it slows down or stay the same in a 22 inch barrel. The gas is still expanding.
wombat25  [Team Member]
3/6/2012 4:47:35 PM
This is a very interesting thread. Thanks for posting.

I thought about this wildcat some time ago, but upon running the cartridge-efficiency-ratio calculations described midway down the page HERE, realized pretty quickly that law of diminishing marginal returns, and the cartridge overall length limitations imposed by the magazine would limit the performance potential of this cartridge. This, combined with the cost of 6.8 brass, pretty much sealed the deal that the .25-223 was the better option for me. The fact that I had a solid stash of .223 brass and magazines didn't hurt.

Anyway, it's interesting to have real-world data to compare. With my .25-223, I can achieve 2900 fps with the 80-grain Barnes TTSX, though my established load chronos at 2860 fps with no pressure signs. With the 100-grain projectiles, 2600 fps is possible, though it seems most users (myself included) have generally settled on loads producing velocities around 2550 fps.

I'll be following this thread closely. All this interest in .257 wildcats is fantastic.



LRRPF52  [Team Member]
3/6/2012 7:49:08 PM
I've been thinking about a .257 Grendel for 3 years now, especially after seeing how .25-06 does with the 115gr Berger VLD's. I think the Grendel is the optimum case for the .257 AR15 if we're talking about case capacity, existing brass, and no limitations in bullet ogive/COAL limitations within the AR15 magazine frame.

Only reason I haven't done it is because I'm pretty diversified and occupied with .260 Rem, Grendel, and 5.56 already. I'm finishing up my business degree, so not much time for experimenting with loads as much as I'd like.
greenhornet-1  [Team Member]
3/6/2012 8:52:48 PM
Thanks for the info. Nice rifle too. Love to the girls at the range.
ricky_arthur  [Member]
3/6/2012 9:00:33 PM
Originally Posted By Siringo:


Here are some of the examples of what I was working with.

Also, the 75 grain Sierra is .757 inches long and the 75 grain VMax is .875 inches long. Big difference. Just look a the difference in the 100 grain Nosler versus the 100 grain Sierras. The Nosler was 100 fps slower ––- because of increase bore surface contact. What are the OAL cartridge lengths you are using for the 75"??

Also, the Burn Rate is not a good indicator of velocity by itself. For instance, a particular powder may have a 100% burn rate in an 18" barrel, but that does not mean it slows down or stay the same in a 22 inch barrel. The gas is still expanding.


Thanks, That is very interesting.

However, regarding the 75 gr Vmax and the 75 Gr Sierra, they are not very different at all. yes the Vmax has a Polymer Tip, but because the sierra is seated to 2.164 and the Vmax to 2.260 they would behave very similarly. The only difference is outside the case and not inside or in bullet/ bore contact area. Stand the 2 side by side and see what I mean.



The Vmax actually has less Bore surface contact because of the boat tail.

Also, do you have any Data on the speer hot core? It looks like the 80gr TTSX is not the bullet for this caliber, so that would be my next thought for a deer load.

Thanks
Siringo  [Member]
3/6/2012 11:04:11 PM
With the 87 grain I was using TAC. Went from 29.0 to 32.4. I thought 32.4 was too hot ––––- so be careful. My notes said to try 32.0, but I never did much more. I have a couple hundred to try, but it may be a few weeks till I get to it.
320pf  [Member]
3/6/2012 11:39:32 PM
I am a big fan of quarterbore cartridges. My fiirst quarterbore was a 25-06. The 25-06 is like shooting high energy particle weapon. It has the trajectory of a laser beam. So now am in the market for a 250-300 Savage bolt action rifle.

When I was working up the 25-223AR I also looked into necking the 6.8 down to 25 cal. Because of the cost of 6.8 brass and the likely need to go with 6.8 mags, I was/am heavily invested in 223 REM/5.56 brass and mags, so I decided to go with the 223 case. Subsequently, the ballistic modeling I have done indicates about 75-100 fps advantage to the 6.8 version.

My load data in 25-223AR using the 75g VMAX (16.5 inch barrel) is about 2950 to 3000 fps using IMR4298 and RE7. With the larger case capacity, I would suggest powders like H335, AA2230, AA2460, and W748. I have not tried using AA220 with the 75 VMAX yet but I suspect the AA220 might be a bit too fast for your 25-6.8SPC cat.

Keep up the good work and keep posting your results.
ricky_arthur  [Member]
3/7/2012 9:46:42 AM
Originally Posted By 320pf:


When I was working up the 25-223AR I also looked into necking the 6.8 down to 25 cal. Because of the cost of 6.8 brass and the likely need to go with 6.8 mags, I was/am heavily invested in 223 REM/5.56 brass and mags, so I decided to go with the 223 case. Subsequently, the ballistic modeling I have done indicates about 75-100 fps advantage to the 6.8 version.

My load data in 25-223AR using the 75g VMAX (16.5 inch barrel) is about 2950 to 3000 fps using IMR4298 and RE7. With the larger case capacity, I would suggest powders like H335, AA2230, AA2460, and W748. I have not tried using AA220 with the 75 VMAX yet but I suspect the AA220 might be a bit too fast for your 25-6.8SPC cat.

Keep up the good work and keep posting your results.



320PF, you have me curious, I haven't looked to hard at the 25-223ar, but I almost sure It would be giving up case capacity to the 6.8 wildcats. Are the velocities you are posting, theoretical numbers, or actual chronograph results? I have a hard time seeing in the 25-223 matching the 25 DTI given the smaller case capacity.. plus with its(the 25-223) longer length, the bullets would be seated even further into the case than with the 6.8 case to make magazine length. It looks like an interesting cartridge, but I don't see how you will get to 2950-3000fps with the 75gr Bullet.

ETA I guess I am forgetting one thing and that is you may be using a 22-24 inch bbl to get those numbers and that would make sense. I am thinking in terms of the 18 inch BBl I have on the 25 DTII.
scatterbrains  [Member]
3/7/2012 10:35:54 AM
im also running a 25-223, my real world numbers im running a 85gr NSBT at 2550fps from a 16" barrel and have zero PSI signs so far. I am using H335. Hopefully ill get to do some more testing this weekend work from 26g up to 27gr and see where i land. im shooting for 3k with the 85gr. I prob wont hit w/o psi signs.

I was going to suggest you look into the 85gr nosler its been fantastic for me so far at 100yds with 3 different powder charges
(ladder testing) i am putting 7rnds in less than an inch.



I am intrigued with the 257 grendal idea though
chris65  [Team Member]
3/7/2012 12:09:11 PM
Originally Posted By ricky_arthur:
Originally Posted By Siringo:
Ricky –––– were did you get your quick load data from????


I got the data from Mike Mili at Dtech, with the exception of the 80gr TTSX and with that I just started low and worked up.


Can you scan and post the data? Also, a chamber print if one was sent also. Thanks.
320pf  [Member]
3/7/2012 2:18:36 PM
Originally Posted By ricky_arthur:
Originally Posted By 320pf:


When I was working up the 25-223AR I also looked into necking the 6.8 down to 25 cal. Because of the cost of 6.8 brass and the likely need to go with 6.8 mags, I was/am heavily invested in 223 REM/5.56 brass and mags, so I decided to go with the 223 case. Subsequently, the ballistic modeling I have done indicates about 75-100 fps advantage to the 6.8 version.

My load data in 25-223AR using the 75g VMAX (16.5 inch barrel) is about 2950 to 3000 fps using IMR4298 and RE7. With the larger case capacity, I would suggest powders like H335, AA2230, AA2460, and W748. I have not tried using AA220 with the 75 VMAX yet but I suspect the AA220 might be a bit too fast for your 25-6.8SPC cat.

Keep up the good work and keep posting your results.



320PF, you have me curious, I haven't looked to hard at the 25-223ar, but I almost sure It would be giving up case capacity to the 6.8 wildcats. Are the velocities you are posting, theoretical numbers, or actual chronograph results? I have a hard time seeing in the 25-223 matching the 25 DTI given the smaller case capacity.. plus with its(the 25-223) longer length, the bullets would be seated even further into the case than with the 6.8 case to make magazine length. It looks like an interesting cartridge, but I don't see how you will get to 2950-3000fps with the 75gr Bullet.

ETA I guess I am forgetting one thing and that is you may be using a 22-24 inch bbl to get those numbers and that would make sense. I am thinking in terms of the 18 inch BBl I have on the 25 DTII.


The 25DTI has about 4.5 to 5 grains (H2O) more case case capacity, 25-223AR holds ~31.31.5 g H2O compared to the 25DTI which I would guess holds about 35-35.5 gr H2O. This is good for about 75-100 fps more velocity (see above). As a general rule, you will get about 1/4 of the percent that you increase case capacity. For example, 5/31 =~16% increase increase in case capacity. This equates to about a 4% increase in velocity ~100-120 fps.

The case length for the 25-223AR is 1.70"... shorter than the 223 REM. The shoulder however for the 25-223AR is the same as he 223 REM.

The actual chronograph results the I have from a 16.5 inch barrel are:

IMR4187==2950
RE7=====3000
IMR4227=3000
A1680===2900

These are all max loads. the estimated pressures are 52000-53000 CUP (55000-60000 psi).

These velocities are not the crazy high. See wombat25's results below.

Originally Posted By wombat25:
Anyway, it's interesting to have real-world data to compare. With my .25-223, I can achieve 2900 fps with the 80-grain Barnes TTSX, though my established load chronos at 2860 fps with no pressure signs. With the 100-grain projectiles, 2600 fps is possible, though it seems most users (myself included) have generally settled on loads producing velocities around 2550 fps.


I like 1/4-bores... Keep up the good work and keep posting your results.
Tim_W  [Member]
3/7/2012 5:44:23 PM
Originally Posted By 320pf:
I

When I was working up the 25-223AR I also looked into necking the 6.8 down to 25 cal. Because of the cost of 6.8 brass and the likely need to go with 6.8 mags, I was/am heavily invested in 223 REM/5.56 brass and mags, so I decided to go with the 223 case. Subsequently, the ballistic modeling I have done indicates about 75-100 fps advantage to the 6.8 version.

.


So you are saying you think a 25/6.8 cat will be 75-100fps faster than a 25/556 cat?
320pf  [Member]
3/7/2012 10:45:41 PM
Originally Posted By Tim_W:
Originally Posted By 320pf:
I

When I was working up the 25-223AR I also looked into necking the 6.8 down to 25 cal. Because of the cost of 6.8 brass and the likely need to go with 6.8 mags, I was/am heavily invested in 223 REM/5.56 brass and mags, so I decided to go with the 223 case. Subsequently, the ballistic modeling I have done indicates about 75-100 fps advantage to the 6.8 version.

.


So you are saying you think a 25/6.8 cat will be 75-100fps faster than a 25/556 cat?


Yep, pretty much. You might get up to 120-130 fps but that would be about it.