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What 7.62x40mm barrel should Noveske make for you

1:12 poly twist

1:12 5 groove conventional twist

1:15 5 groove conventional twist

1" gas block seat with pinned .750" Noveske block

1" long .750" gas block seat with no gas block

1.9" long .750 gas block seat with no gas block

16" heavy contour mid-length gas system

16" Recon contour carbine length gas system

16" Recon contour mid-length gas system

20" heavy contour mid-length gas system


















(115)  17.8%

(55)  8.5%

(9)  1.4%

(76)  11.8%

(27)  4.2%

(27)  4.2%

(38)  5.9%

(53)  8.2%

(165)  25.6%

(80)  12.4%
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762x40mm
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Posted: 6/15/2008 5:40:04 PM
[Last Edit: 10/22/2012 4:06:39 PM by 762x40mm]
The 7.62x40mm is a .223 based wild-cat offering for the service rifle family of weapons and was created by Kurt Buchert of Lake Charles, Louisiana.

First thoughts began in September of 2005 as the result of many sleepless Hurricane Rita nights huddled around lanterns thinking and talking about the use of the 300-221 as a medium-sized game hunting cartridge in a service rifle platform. The thought or goal was to wild-cat an improved .30 caliber cartridge that would take advantage of as much of the .223 parent case capacity with a 125 grain bullet and still load and function in standard service rifle magazines and mechanism components. The selection of the .30 caliber projectile in this weight class was based on the calculated velocity window of 2,400 to 2,500 fps and decades of industry wide reloading, hunting, and military experience. The compiled information showed that the 110 to 125 grain projectiles performed well at these intermediate velocities while delivering modest recoil and a high degree of controllability and accuracy in manual and gas operated weapons.

Following the intermediate cartridge concept of the 7.92x33mm kurz, 7.62x39mm Russian, 7.92x40mm CETME, and 7.62x40mm CETME from the 40’s and 50’s the 7.62x40mm is a culmination of firearms industry, wild-cat, benchrest, and personal experience and information. The chamber dimensions went through several revisions in an effort to produce the best all-around compromise of feeding, case capacity, velocity, accuracy, and chamber release. The intersection of these efforts has come to what individual owners and industry leaders spoken with have called a “makes-sense” cartridge for intermediate power in a service rifle platform.

Cartridge Data
Case length: 39.76mm / 1.565”
Case rim: .378"
Case rim thickness: 0.045"
Case base: .373"
Case taper: 0.011” total
Case shoulder angle: 30°
Case Capacity: appx 30 grains of de-mineralized H20, varies slightly by brass manufacturer.
Maximum loaded overall length (OAL) in AR15 magazines: appx 2.250", varies by manufacturer of magazine.
Usable case capacity with a 125gr flat-base bullet seated magazine length is appx 26.5 grains of Accurate 1680 powder, varies slightly by brass manufacturer.
Rifling twist rate varies from 1:8 to 1:14

Average Performance Data

16” Barrel
110 Hornady V-MAX =2,575 fps
110 Sierra Varmint = 2,550 fps
125 Speer TNT = 2,450 fps
125 Nosler BTBT = 2,450 fps
123 Lapua FMJ = 2,475

20” Barrel
110 Hornady V-MAX =2,700 fps
110 Sierra Varmint = 2,675 fps
125 Speer TNT = 2,600 fps
125 Nosler BTBT = 2,575 fps
123 Lapua FMJ = 2,625 fps



Cartridge and System Information

The 7.62x40mm is derived from the 5.56x45mm (.223 Rem.) parent case. The low cost and availability of mil-surplus and commercial brass was one of the core reasons for the development of this cartridge.

Primarily designed to use 7.62mm (.308) projectiles in the 110 to 125gr range, but has been loaded and tested up to 220gr in sub-sonic applications. The range of bullet weights and designs in the .308 family make this a very flexible cartridge.

The user selectable ballistic performance makes it an excellent choice for varmint control, medium sized game hunting, or personal defense. As illustrated below in a comparison of the .223 and 7.62x40mm.

.223 load of a 55gr FMJBT at 3,000 fps will produce an average of:
1,100 ftlbs of energy at the muzzle
885 at 100 yards
710 at 200 yards
565 at 300 yards with a 5.4” high flight path

7.62x40mm load of a 125gr BTBT at 2,500 fps will produce an average of:
1,730 ftlbs of energy at the muzzle
1,430 at 100 yards
1,175 at 200 yards
960 at 300 yards with a 7.6” high flight path

The 7.62x40mm makes the most of standard rifle components, usually only requiring a barrel change while still offering the end user the ability to customize the rifle with their choice of buffer and gas systems. You can still tune the rifle for timing and felt recoil which makes the whole system more user friendly and reduces wear and tear on the rifle, does not require any proprietary parts to function.

For current 300-221 / 300 Whisper users it is a natural progression if looking for more velocity. Simply have the barrel re-chambered, cut and form new brass, adjust your reloading dies for the longer round, reload and head to the range.

The information in this document is not inclusive of all that has gone into the 7.62x40mm cartridge, the thousands of rounds reloaded and fired, experiments with magazines, chamber revisions and results, or the performance of barrel and gas system length…..

This is meant to serve as core information, a conversation starter, and a holding area for those who wish to share their experience with the 40...

line-up of 300-221, 7.62x40mm, .25x40mm, 5.56x45mm



A few firearms chambered in 7.62x40mm and die set...










JFA
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Posted: 6/15/2008 9:20:11 PM
The other fellow that posted on this cartridge got your 16 " barrel velocities out of his 20 " barrel, so what goes there? Are your velocities actual tested and proven ones? What's the advantage of this cartridge over the 7.62x39 or even both the 6.8 SPC & 6.5 Grendel necked to 30 caliber besides the bolt is stronger because of more meat in the face of it? Forget magazines, which by the way the other poster said require some grinding as you can't just use a ordinary 5.56 magazine. I'd also do a better comparison with the 223 using a better bullet such as the military is using now instead of the very first bullet that ever came out with it too. The heavier high BC 223 projectiles shoot much flatter and farther then many rounds, especially the old 55 gr BT.

Not knocking your round just saying present it 100% truthfully. One more thing, if it's so good why did the Military take a harder look at the 6.8 SPC?
762x40mm
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Posted: 6/15/2008 10:24:55 PM
[Last Edit: 6/15/2008 10:55:19 PM by 762x40mm]

Originally Posted By JFA:
The other fellow that posted on this cartridge got your 16 " barrel velocities out of his 20 " barrel, so what goes there? Are your velocities actual tested and proven ones?


The rifle that uptown1 posted about is a 16" barrel with a carbine length gas system and produced the same appx velocities (within 50 to 75fps) that we listed for a 16" barrel in our thread, and yes I can assure you that the velocities are actually tested and proven....I have pulled my RCBS Rock Chunker to the tune of about 2,500 times loading for this cartridge over the last year.....


Originally Posted By JFA:
What's the advantage of this cartridge over the 7.62x39 or even both the 6.8 SPC & 6.5 Grendel necked to 30 caliber besides the bolt is stronger because of more meat in the face of it? Forget magazines, which by the way the other poster said require some grinding as you can't just use a ordinary 5.56 magazine.


The 7.62x39 Russian generally uses .310 projectiles, a quick look at Midway showed 9 or 10 bullets to choose from....the 7.62x40 uses .308 projectiles, the same search showed over 300 bullets to choose from.....you hit the nail on the head, the standard bolt has more meat (stronger face).....I have used standard metal mags, modified metal mags, standard pmags, and de-ribbed pmags....they all work....as any AR shooter has done with any caliber (5.56, 7.62x39,....) there are things that you can do to give a greater sense of security with your mags (change spring tension, add the best and new followers, the latest and greatest slick coating) any mods that I or other shooters have done to their 300-221, 300 whisper, or 7.62x40 mags is for the same sense of security more so than a mechanical requirement.....if you necked up the 6.5 to 30cal you would end up with a 7.62x39 with less case taper and a 30 degree shoulder, we actually thought about doing this (written about in uptown1's thread) to make it fit better in standard curve mags, opted not to do this for a few different reasons....


Originally Posted By JFA:
I'd also do a better comparison with the 223 using a better bullet such as the military is using now instead of the very first bullet that ever came out with it too. The heavier high BC 223 projectiles shoot much flatter and farther then many rounds, especially the old 55 gr BT.


20" barrel vs. 20" barrel...the 62gr SS109 spec calls for use in a 20" barrel with the velocity measured 25 meters from the muzzle (3,025fps)....if you change the 40 to a 20" barrel the velocity goes up over 100fps (2,600fps)....either way the 40 produces more energy...not to entertain a "my cartridge is better than your cartridge" debate but the comparison information was put in the thread using the load that has been around the longest therefore more people should be the most familiar with.

.223 load of a 62gr FMJBT SS109 at 3,000 fps will produce an average of:
1,239 ftlbs of energy at the muzzle
1,022 at 100 yards
842 at 200 yards
689 at 300 yards with a 5.25” high flight path

7.62x40mm load of a 125gr BTBT at 2,600 fps will produce an average of:
1,876 ftlbs of energy at the muzzle
1,553 at 100 yards
1,281 at 200 yards
1,048 at 300 yards with a 7.1” high flight path



Originally Posted By JFA:
Not knocking your round just saying present it 100% truthfully. One more thing, if it's so good why did the Military take a harder look at the 6.8 SPC?


From everything I can see in the thread and my response it is being presented 100% truthful....if there is something that is coming across as a mistake or misleading in the thread or my response please point it out and I will try to clear it up....I think the 6.8 is a great cartridge....great, but different...
320pf
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Posted: 6/15/2008 10:49:31 PM
JFA,


Originally Posted By JFA:
The other fellow that posted on this cartridge got your 16 " barrel velocities out of his 20 " barrel, so what goes there?


Are you referring to the thread started by "uptown1"? Unless I completely read his post and associated threads incorrectly, I think that he has a 16-inch barrel. The velocities that "uptown1" gives are:

"this build will be dedicated to super-sonic use and was told to expect top-end velocities between 2,400 and 2,700 fps depending on the weight of the bullet, was shooting 125 TNT's at 2,450 fps today. it will also shoot 180 to 220gr sub-sonic, but thats what I'll use the Whispers for."

And:

"I went to the range and tested the 125 noslers yesterday, had them clocking right at 2,500fps. The best I can figure is some where around 975 foot lbs of energy at 300 yards."

These are pretty much the velocities that are listed by 762x40mm in his above post.


Originally Posted By JFA: What's the advantage of this cartridge over the 7.62x39 or even both the 6.8 SPC & 6.5 Grendel necked to 30 caliber besides the bolt is stronger because of more meat in the face of it? Forget magazines, which by the way the other poster said require some grinding as you can't just use a ordinary 5.56 magazine.


One of the big advantages is as you say... uses a standard bolt. I am not sure if you have to modify the mags to get them to work. I would like to know if unmodified mags work as well.



Originally Posted By JFA:One more thing, if it's so good why did the Military take a harder look at the 6.8 SPC?


I think that the answer to this question is that the folks that put the 6.8 SPC and 6.5 G together were looking for 300 yard plus performance better than the 5.56mm and similar to 7.62x57mm (308W).

For CQB however, I think that the 7.62x40mm or 300-Whisper with a bullet design similar to the Speer 125 g TNT or a Berger 125 or 135 g bullet (The equivalent to an open tip match OTM) would be very effective.

Any way we now have another wildcat AR15 variant to consider.

320pf
JFA
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Posted: 6/15/2008 10:50:58 PM
Thanks for the update.

I can tell you that the Grendel necked up will hold more powder and the PPC case is much much more efficient too, but still you end up with the thinner bolt face. That's soon to change I hear.

As for the 7.62x39 using .310 bullets, most the barrels I've seen out for them are actually .308 so that negates that bullet selection.
762x40mm
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Posted: 6/15/2008 11:04:28 PM
[Last Edit: 6/15/2008 11:17:20 PM by 762x40mm]

Originally posted by JFA:
As for the 7.62x39 using .310 bullets, most the barrels I've seen out for them are actually .308 so that negates that bullet selection.


Every barrel manufacturer 6 or 7 that I talked to about blanks follow the same take as mainstream maufactures (Colt, Ruger,....) refuse to chamber 7.62x39mmRussian for use with .308 bullets, even if you promise and promise to reload only for it.....they are afraid that someone will shoot import .310 ammo in place of the .308 and need a bandaid....I have heard of people getting them but not many...so the bullet selection issue is alive and well....

320pf and JFA.....thanks for even looking at the thread and responding with comments....

I had even looked over the information that uptown1 wrote that 320pf pointed out or I would have jumped all over that

320pf...I shot some 110grain hollow points a few days ago right at 2,700fps into a metal plate at 100 yard....man, it hit like a hammer....I cant imagine what it would do to a coyote sized animal....

thanks again

40
uptown1
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Posted: 6/16/2008 12:22:40 AM
[Last Edit: 6/16/2008 12:23:12 AM by uptown1]
I just noticed a little while ago that the info thread had been started.

Just finished reading the above posts.

All I will say is this....I met him for the first time at the Lake Charles range and this guy who I had never met handed me my new rifle with a load of (30) 40's in it pointed down-range and said "tear it up"....never having even held the rifle before I centered up on the 200yd plates and proceded to dump a mag.....all hits, empty mag, no jams, big fucXXng stupid smile on my face....

I AM VERY HAPPY WITH MY RIFLE AND THE 40.....I am not saying this to start a debate, or "my cartridge is better than your cartridge" but if you read my other posts and read between the lines you can probably add up that I have had close to (10) AR-15's including a 7.62x39 (boy I really loved shooting 5 rounds) I know, I know, I know that is changing with the new mags, but that was the situation I was in with it a few years ago and oh by the way, would you like those 5 rounds with a 123gr bullets or a 123gr bullets....boy I'm not making any friends here....

When I got my first 300 fireball I absopositivly found a new home, .223 brass, standard mags that would actually hold and fire 30 rounds, performance just a little under Russian velocity, which you could make up for by using a better .308 bullet at longer ranges. As Kurt put it 'the 40 is a natural progression for anyone who has a 300-221 and looking for more velocity.

Kurt is probably one the most straight forward honest people I have met, sometimes a little too serious, thats why I wrote the post the other day jackin with him about the subs.....If he tells ya the sky is red you'd better get ready for sunset.

uptown1..........out
moose01
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Posted: 6/16/2008 5:07:20 AM
Regarding twist rates; let's say you primarly want to shoot the 110gr Vmax or 123-125 pills, but on occassion would like to handle the heavier loads for subsonic use. What twist rate would you recommend? What would you recommend if you only planned on using 110-125gr loads?
762x40mm
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Posted: 6/16/2008 6:10:55 AM
[Last Edit: 6/16/2008 6:12:10 AM by 762x40mm]

Originally Posted By moose01:
Regarding twist rates; let's say you primarly want to shoot the 110gr Vmax or 123-125 pills, but on occassion would like to handle the heavier loads for subsonic use. What twist rate would you recommend? What would you recommend if you only planned on using 110-125gr loads?


We have used the Greenhill Formula in the past to calculate twist....

Personal experience with the 300 Whisper, 30x47 (benchrest cartridge), and the 7.62x40 has shown me a lot with twist rate.....


Originally Posted By moose01:
Regarding twist rates; let's say you primarly want to shoot the 110gr Vmax or 123-125 pills, but on occassion would like to handle the heavier loads for subsonic use.


If by heavier subsonics you mean something along the lines of a 220 Matchking at 1050fps, that would require something along the lines of a 1:7.5 to 1:8.....the 110gr Vmax at the velocity you could expect with the '40' is around 2,600 to 2,700 fps as low as a 1:18 will work.....the 123-125 pills around 2,500 fps a 1:14 will work...........As you can see with a velocity window from 1,050 to 2,700fps with projectiles from 110 to 220gr, the twist to stabilize changes from 1:7.5 to 1:18......

If building a multi use 30 cal rifle for the ranges that I shoot at I would probably pick something like a 1:10.....won't impart too much twist friction and slow down the supers too bad, the heavy subs accuracy may suffer a little but you could expect them to yaw and tumble quite nicely....


Originally Posted By moose01:
What would you recommend if you only planned on using 110-125gr loads?


Benchrest shooting the 30x47 and experimenting with the '40' has shown me that at velocities between 2,500 and 2,700 fps the 110-125 projectiles will work in twists between 1:12 to 1:18.....would probably go with something around a 1:12....

Thanks

'40'
ARmory04
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Posted: 6/16/2008 6:34:46 AM

This is great info, and thanks for your work! It's nice to see a fellow 'Louisianian' coming out with a wildcat!


If I could ever get some other projects out of the way, you will be hearing from me! I would definitely love to meet up and put the round through its paces.

Few Q's:

-Are you planning on marketing/selling any 7.62x40 barrels, parts, dies, etc?
-What kind of accuracy testing has been done?
-Do you have a comprehensive reloading sheet w/ powders, primers, etc?


Thanks again for your work!
JFA
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Posted: 6/16/2008 3:45:49 PM
[Last Edit: 6/16/2008 3:56:45 PM by JFA]

Originally Posted By 762x40mm:

Originally posted by JFA:
As for the 7.62x39 using .310 bullets, most the barrels I've seen out for them are actually .308 so that negates that bullet selection.


Every barrel manufacturer 6 or 7 that I talked to about blanks follow the same take as mainstream maufactures (Colt, Ruger,....) refuse to chamber 7.62x39mmRussian for use with .308 bullets, even if you promise and promise to reload only for it.....they are afraid that someone will shoot import .310 ammo in place of the .308 and need a bandaid....I have heard of people getting them but not many...so the bullet selection issue is alive and well....

320pf and JFA.....thanks for even looking at the thread and responding with comments....

I had even looked over the information that uptown1 wrote that 320pf pointed out or I would have jumped all over that

320pf...I shot some 110grain hollow points a few days ago right at 2,700fps into a metal plate at 100 yard....man, it hit like a hammer....I cant imagine what it would do to a coyote sized animal....

thanks again

40


I believe the Ruger Mini 30 is indeed a .308 groove diameter. Colt is not as you say. Also my DPMS barrel (made by Wilson Arms) is not .310 either.
762x40mm
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Posted: 6/16/2008 8:15:43 PM
[Last Edit: 6/16/2008 8:17:12 PM by 762x40mm]

Originally Posted By ARmory04:
This is great info, and thanks for your work! It's nice to see a fellow 'Louisianian' coming out with a wildcat!


If I could ever get some other projects out of the way, you will be hearing from me! I would definitely love to meet up and put the round through its paces.

Few Q's:

-Are you planning on marketing/selling any 7.62x40 barrels, parts, dies, etc?
-What kind of accuracy testing has been done?
-Do you have a comprehensive reloading sheet w/ powders, primers, etc?


Thanks again for your work!


I make runs out to the range just about every weekend....come around and we can dump a few mags....

I don't know if you would call it marketing, but I would like to keep a few more barrels on hand for the interested....there is always a new combination to try....hell, I might even build one for .310 or .311 projectiles, just so I can say I have one...and never shoot it

I have used the 300 whisper dies (Hornady) and 300-221 dies (Redding) and they work great....I think a '40' specific full-length sizing die would be really neat......right now just neck sizing with the Redding works great, chambers and cycles fine but the standard 300 full length sizer Hornady or Redding tries to put too much of the Whisper taper back in....kinda defeats the purpose of blowing the case walls and shoulder out....I am working on having 40 specific dies made..

The accuracy has been great with both the 16 and 20"......usually around MOA....It has been so windy the last several time at the range it has been pretty tough to shoot for groups....the post that uptown1 put up has a couple links to some targets we shot the day he picked his 40 up.....the 110gr target is a pretty neat tool to show the effect that wind has on the 110's, each shot was fired center, the wind caused the drift....compare it to the 125's, they grouped not too bad in the same wind...

www.quarterbore.net/forums/photopost/showphoto.php?photo=501&cat=529
www.quarterbore.net/forums/photopost/showphoto.php?photo=500&cat=529

I have around forty working loads for the '40' 110 to 220gr from 1,000 to 2,700fps.....there were more initial loads but 20 or so fell into the 'well, that one didn't work' catagory....usually due to using too fast of a powder in a long gas system...

thanks for the interest,

'40'
762x40mm
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Posted: 6/16/2008 8:29:07 PM

Originally Posted By uptown1:
I just noticed a little while ago that the info thread had been started.

Just finished reading the above posts.

All I will say is this....I met him for the first time at the Lake Charles range and this guy who I had never met handed me my new rifle with a load of (30) 40's in it pointed down-range and said "tear it up"....never having even held the rifle before I centered up on the 200yd plates and proceded to dump a mag.....all hits, empty mag, no jams, big fucXXng stupid smile on my face....

I AM VERY HAPPY WITH MY RIFLE AND THE 40.....I am not saying this to start a debate, or "my cartridge is better than your cartridge" but if you read my other posts and read between the lines you can probably add up that I have had close to (10) AR-15's including a 7.62x39 (boy I really loved shooting 5 rounds) I know, I know, I know that is changing with the new mags, but that was the situation I was in with it a few years ago and oh by the way, would you like those 5 rounds with a 123gr bullets or a 123gr bullets....boy I'm not making any friends here....

When I got my first 300 fireball I absopositivly found a new home, .223 brass, standard mags that would actually hold and fire 30 rounds, performance just a little under Russian velocity, which you could make up for by using a better .308 bullet at longer ranges. As Kurt put it 'the 40 is a natural progression for anyone who has a 300-221 and looking for more velocity.

Kurt is probably one the most straight forward honest people I have met, sometimes a little too serious, thats why I wrote the post the other day jackin with him about the subs.....If he tells ya the sky is red you'd better get ready for sunset.

uptown1..........out



wow....thanks.....
bfarrin1
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Posted: 6/16/2008 8:29:31 PM

Originally Posted By JFA:
As for the 7.62x39 using .310 bullets....

....most the barrels I've seen out for them are actually .308 so that negates that bullet selection.

I believe the Ruger Mini 30 is indeed a .308 groove diameter.

Colt is not as you say.

Also my DPMS barrel (made by Wilson Arms) is not .310 either.



Hmm.


www.ar15.com/forums/topic.html?b=3&f=121&t=378624


Originally Posted By JFA:

That's funny on the Wilson barrel because mine slugs .3095 in the grooves.

I knew the Colt would be .310 dead on the money.



Have I missed something in the translation here?

So, who's "most" barrels are .308 groove diameter?



762x40mm
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Posted: 6/16/2008 8:36:24 PM
[Last Edit: 6/16/2008 9:00:30 PM by 762x40mm]

Originally Posted By bfarrin1:

Originally Posted By JFA:
As for the 7.62x39 using .310 bullets....

....most the barrels I've seen out for them are actually .308 so that negates that bullet selection.

I believe the Ruger Mini 30 is indeed a .308 groove diameter.

Colt is not as you say.

Also my DPMS barrel (made by Wilson Arms) is not .310 either.



Hmm.


www.ar15.com/forums/topic.html?b=3&f=121&t=378624


Originally Posted By JFA:

That's funny on the Wilson barrel because mine slugs .3095 in the grooves.

I knew the Colt would be .310 dead on the money.



Have I missed something in the translation here?

So, who's "most" barrels are .308 groove diameter?





bfarrin1, thanks for the link....I wasn't even gonna try....

I don't even care about that discussion anymore (308 groove 310 groove kinda contradictive from post to post, and probably starting to tase a lot like crow) ....bfarrin1 I wanna know what the hell that is on your avatar....dude that is cool....
JFA
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Posted: 6/16/2008 9:51:59 PM

Originally Posted By bfarrin1:

Originally Posted By JFA:
As for the 7.62x39 using .310 bullets....

....most the barrels I've seen out for them are actually .308 so that negates that bullet selection.

I believe the Ruger Mini 30 is indeed a .308 groove diameter.

Colt is not as you say.

Also my DPMS barrel (made by Wilson Arms) is not .310 either.



Hmm.


www.ar15.com/forums/topic.html?b=3&f=121&t=378624


Originally Posted By JFA:

That's funny on the Wilson barrel because mine slugs .3095 in the grooves.

I knew the Colt would be .310 dead on the money.



Have I missed something in the translation here?

So, who's "most" barrels are .308 groove diameter?





Yeah you have. Tell me how a .310 groove makes a difference when most the 7.62x39 ammo have bullets that average .311 minumum? A lot measure .3115 and larger. Because bore and groove diameters were all over the map on 7.62x39 barrels, and bullet equally all over the map, it was hard for American barrel manufacturers to decide what to settle on. Ruger first came out with their Mini 30 with a .308 groove and a forcing cone that swaged the bullet down. When it was heard that Ruger's accuracy wasn't so great with surplus they made a change after a certain serial number production. The change was made to try correct the inaccuracy, not because of a pressure problem, which their isn't a pressure problem with 7.62x39 ammo. So wouldn't you say .311 or larger would be just as "dangerous by the barrel makers opinions" in my Wilson barrel as a .310 bullet would be in a .308 groove barrel?

I think the barrel manufacturers gave that as a generic answer when more then like they didn't what to tool and set up for two different very closer 30 caliber bore and groove diameters.

Another common caliber and rifle that has a small dimension bore and groove diameter is the 7.5 Swiss and yet the the .308 bullet is very much loaded in it.

Tell all the story bfarrin1
uptown1
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Posted: 6/16/2008 11:03:50 PM
height=8
Originally Posted By JFA:

As for the 7.62x39 using .310 bullets, most the barrels I've seen out for them are actually .308 so that negates that bullet selection.


are "most" 7.62x39 barrels you've seen in .308 or are "most" of the ones you own in .308?

going by your posts it looks like the ones you own or atleast held in your hands long enough to slug checked at .310....oh, I'm sorry .310 and .3095...

shoot .308 bullets through your .310 colt....I did, looked like buck-shot...

most(a): (superlative of `many' used with count nouns and often preceded by `the') quantifier meaning the greatest in number; "who has the most apples?"; "most people like eggs"; "most fishes have fins" "most 7.62x39 barrels are not for .308 bullets"
bfarrin1
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Posted: 6/17/2008 6:26:41 AM

Originally Posted By JFA:
Tell all the story bfarrin1


Best I can tell, you're the one spinning the tale - which now seems to be spinning in the "who care's about groove diameter" direction.


In calling your Wilson at .3095 "not" .310" is like calling a .3075 Krieger tight Palma barrel "not" a .308.


But, I digress - If there are off the shelf AR-15 .308 groove 7.62x39 barrels to be found, I'd like to have one. If there isn't, I'm going to spin a couple up myself.





JFA
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Posted: 6/17/2008 11:12:24 AM

Originally Posted By bfarrin1:

Originally Posted By JFA:
Tell all the story bfarrin1


Best I can tell, you're the one spinning the tale - which now seems to be spinning in the "who care's about groove diameter" direction.


In calling your Wilson at .3095 "not" .310" is like calling a .3075 Krieger tight Palma barrel "not" a .308.


But, I digress - If there are off the shelf AR-15 .308 groove 7.62x39 barrels to be found, I'd like to have one. If there isn't, I'm going to spin a couple up myself.







Now there's the point....spinning your own. That negates everything said about the 7.62x39 before, doesn't it??
J-A-R
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Posted: 6/17/2008 3:54:40 PM
The 7.62x40mm sounds like a well thought out wildcat for the AR platform. I look forward to hearing more about its development.

Joe
bfarrin1
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Posted: 6/17/2008 7:08:44 PM

Originally Posted By JFA:
Now there's the point....spinning your own. That negates everything said about the 7.62x39 before, doesn't it??


You're throwing chaff.

If you've got a source for .308 groove AR-15 7.62x39 barrels, please enlighten us.


762x40mm
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Posted: 6/17/2008 7:27:05 PM

Originally Posted By J-A-R:
The 7.62x40mm sounds like a well thought out wildcat for the AR platform. I look forward to hearing more about its development.

Joe


Thanks for the compliment and interest, as I learn more about the manufacturing side of the industry (dies, brass, barrels,...) I will definitely pass it on....

Thanks again,

'40'
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Posted: 6/17/2008 8:01:54 PM
I have 2 uppers chambered for the 6x45mm Wildcat one in a 20" and the other a 16" barrel. So with getting my feet wet on this wildcat have also considered others like the 300/221 fireball, but was more interested in the Super Sonic application of this cartridge. Your 762x40mm looks to be a good choice for those wanting a little more velocity while keeping the AR as close to stock as possible. Thanks for taking the time to post it here on AR15.com.

Joe
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Posted: 6/17/2008 8:22:12 PM

Originally Posted By J-A-R:
I have 2 uppers chambered for the 6x45mm Wildcat one in a 20" and the other a 16" barrel. So with getting my feet wet on this wildcat have also considered others like the 300/221 fireball, but was more interested in the Super Sonic application of this cartridge. Your 762x40mm looks to be a good choice for those wanting a little more velocity while keeping the AR as close to stock as possible. Thanks for taking the time to post it here on AR15.com.

Joe


I have been a long time fan of the 300-221 / Whisper, still own and shoot several of them.....and as the intro post suggests this was targeted as a super-sonic improvement...

How does the 6x45 work out......what is the largest grain bullet you have tried....the VLD's are pretty slick....

thanks again

'40'
Bearbait1
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Posted: 6/17/2008 9:00:55 PM
762,

I too want to thank you for the write-up. I am also very interested, as I have an MGI switch barrel platform, in 22LR, 556, 6x45 and 458 Socom. I really would like to add one more caliber between the 6 and 458 for Mule deer and possibly Elk. The 6x45 is, imho, a little thin for mule deer and certainly elk. The 458 is certainly big enough, but your 762x40 energy figures look pretty decent out to 300 yards. The major plus for me on your round is that standard AR mags work. As I keep my entire system in a single case, not having to fiddle with unique mags would be very nice. I am guessing that while the velocity is several hundred fps slower than a 308, there are enough bullets in 308 caliber available to meet anyones design needs. Very nice.

As to your 6x45 query, I'll let the other poster add his thoughts, but add some myself. The major problem with the 6x45 is the lack of neck/shoulder relocation with the heavier bullets. I have found that about 85 grains of HP bullet to be about max for the cartridge. The really sleek, heavier pointed bullets just do not have the magazine room to fit the ogive of the bullets properly. I am sure that you understand this issue probably better than me. But, the 6x45 is a pretty sweet round. Like yours, bolts brass and mags are cake. And the 85TSX bullet works and works well, driven to 2700 fpsish on intermediate size game, like pronghorn and probably white tail deer. The biggest selling points are ease of reloading, common AR parts, and the magical 6mm diameter that makes it legal in many more states than the 556 round.

Please keep us posted on your exploits, and lets hope the guys that want to nit pick your write-up go back to the 6.5 v. 6.8 debate where they like to get pretty hostile. I mean, JHC, I could give a rats ass what the Military chooses for our troops, other than they get what they need (the comment about if your 762 is so good why did the military dismiss it). The rest of us who are not in the military can pick and choose what we need for our design requirements. Just post your results, and those of us intelligent enough can figure out whether it will work for OUR needs. This Board is full of "my cartridge is better than yours". You gotta let it go. There are a few here who will attempt to bait you into a pissing match.

Craig
Northern born and Southern Bred
bfarrin1
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Posted: 6/17/2008 9:14:28 PM
[Last Edit: 6/17/2008 9:15:28 PM by bfarrin1]
40,

Have you finalized the reamer print...?

Ben Syring at Hornady is the fellow to talk to right now, in my opinion, for custom dies.

They've been delivering dies for me in about 8 weeks lately, and they've all been built to print....which is something I can't say for some of the other folks I've used in the past.

Just call the main line into Hornady, ask for Ben or the custom shop - he'll set you up in short order. He'll likely ask for three pieces of fired brass for verification.



The little cartridge in my avatar you asked about is the 358 BFG/WSSM.

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