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Posted: 6/15/2008 4:40:04 PM EST
[Last Edit: 10/22/2012 3:06:39 PM EST 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...











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Link Posted: 6/15/2008 8:20:11 PM EST
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?

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Link Posted: 6/15/2008 9:24:55 PM EST
[Last Edit: 6/15/2008 9:55:19 PM EST 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...

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Link Posted: 6/15/2008 9:49:31 PM EST
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

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Link Posted: 6/15/2008 9:50:58 PM EST
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.

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Link Posted: 6/15/2008 10:04:28 PM EST
[Last Edit: 6/15/2008 10:17:20 PM EST 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

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Link Posted: 6/15/2008 11:22:40 PM EST
[Last Edit: 6/15/2008 11:23:12 PM EST 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

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Link Posted: 6/16/2008 4:07:20 AM EST
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?

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Link Posted: 6/16/2008 5:10:55 AM EST
[Last Edit: 6/16/2008 5:12:10 AM EST 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'

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Link Posted: 6/16/2008 5:34:46 AM EST

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!

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Link Posted: 6/16/2008 2:45:49 PM EST
[Last Edit: 6/16/2008 2:56:45 PM EST 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.

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Link Posted: 6/16/2008 7:15:43 PM EST
[Last Edit: 6/16/2008 7:17:12 PM EST 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'

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Link Posted: 6/16/2008 7:29:07 PM EST

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.....

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Link Posted: 6/16/2008 7:29:31 PM EST

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?




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Link Posted: 6/16/2008 7:36:24 PM EST
[Last Edit: 6/16/2008 8:00:30 PM EST 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....

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Link Posted: 6/16/2008 8:51:59 PM EST

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

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Link Posted: 6/16/2008 10:03:50 PM EST
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"

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Link Posted: 6/17/2008 5:26:41 AM EST

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.


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Link Posted: 6/17/2008 10:12:24 AM EST

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??

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Link Posted: 6/17/2008 2:54:40 PM EST
The 7.62x40mm sounds like a well thought out wildcat for the AR platform. I look forward to hearing more about its development.

Joe

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Link Posted: 6/17/2008 6:08:44 PM EST

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.



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Link Posted: 6/17/2008 6:27:05 PM EST

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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Link Posted: 6/17/2008 7:01:54 PM EST
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.

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Link Posted: 6/17/2008 7:22:12 PM EST

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

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Link Posted: 6/17/2008 8:00:55 PM EST
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.

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Link Posted: 6/17/2008 8:14:28 PM EST
[Last Edit: 6/17/2008 8:15:28 PM EST 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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Link Posted: 6/17/2008 8:35:23 PM EST
Thanks for the interest and the info on the 6x45......we had looked at doing a similar cartridge as the '40' in 6mm or 6.5mm.....as you pointed out, shoulder placement is critical for the scenar or vld type bullets....by the time you get the shoulder far enough back to get the bullet in the mag you end up having to increase case diameter to get the powder charge up ...ala 6.5grendel....


Originally Posted By Bearbait1:

The major plus for me on your round is that standard AR mags work.


what kind of mags do you favor....I'm really starting to like the pmags....inexpensive, tough....at first I didn't care for the size of the floor plate, but it started to grow on me as I could reach for a mag not looking and instantly knew which end I had....


Originally Posted By Bearbait1:

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.

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.


I don't mind.....I think "most" (pun intended) people realize the world is round and not flat.....besides, I know what works for me....

Thanks again for the positive comments...

'40'

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Link Posted: 6/17/2008 8:52:10 PM EST

Originally Posted By bfarrin1:

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


cooool....I can think of a couple things that BFG could stand for....thats really neat


Originally Posted By bfarrin1:

Have you finalized the reamer print...?.


I guess as finalized as its going to get....for now, I guess, I like to tinker too much...hopefully its being cut this or next week....I can't say enough good about David Kiff, every time I have called PTG him and the crew there have been very friendly and helpful.....



Originally Posted By bfarrin1:

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


That is exactly what I needed....thank you so much....

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Link Posted: 6/17/2008 10:03:25 PM EST
I'll finish your first comment, once you get the diameter of the case up, you run into magazine problems.

As to magazines, I am definately not a whore, and basic is good. I like the older Colts, newer Brownells, some from Bravo Company, a few from Bushmaster. Just good ol' 20 and thirty rounders, with Magpul followers, and at least one in each caliber with Ranger floorplates. All three of my 556 barrels, my 6x45 and 458 don't care which one is used. I have one full mag dedicated to each caliber in my case, and a few other empty mags that get rotated through all of the barrels in my single upper/lower. I have 5 barrels and bolts (one of which is a Ciener conversion with RPK barrel), one upper, one lower, one Nightforce scope, one Leupold scope, one JPoint, sling and few other goodies all neatly crammed into one 1600 Pelican case. It is nice not to worry about mag sorting. Pop the lid, insert upper onto lower, install barrel, slide in bolt/carrier and grab a mag. Good to go. A 7.62x40 would feel right at home in the case.

Perhaps one day. I like to use Marty of Teppo Jutsu for my custom calibers, so I was happy when I saw he posted in this thread. I had a thirty caliber conversation with him years ago when I bought the 458S from him. I think the Whisper was about it back then. Might start twisting his arm if your 7.62 is available for others to play with.

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Link Posted: 6/17/2008 10:13:26 PM EST
I just ordered my first AR kit and was contemplating a 6.8/7.62/300-221 instead of 5.56. I ended up going with the standard cal since I already had mags and wouldn't have ammo supply issues.

However, the .300 Whisper really piqued my interest and I would have went with it right out of the box had it not been for having to form brass and cut so much of the darn case to bring it to .221 Fireball size. This cartridge seems just the ticket for similar performance (better in supersonic mode) and less work for the handloader forming from 5.56 brass.

How much of a 5.56 formed case do you need to trim off? Plan on doing any test with 240gr subsonics? I think that and 123gr supersonic deer hunting loads would be my intended use. If I ever get around to ordering a .300 barrel, I'll need to hook up with you for a recut chamber.

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Link Posted: 6/17/2008 10:30:22 PM EST

Originally Posted By Bearbait1:
I'll finish your first comment, once you get the diameter of the case up, you run into magazine problems.


yep....in an earlier post I commented about making a kinda of .308 7.62x39 Russian, with less case taper and sharper shoulder...that was one of the primary reasons we didn't...


Originally Posted By Bearbait1:
As to magazines, I am definately not a whore, and basic is good. I like the older Colts, newer Brownells, some from Bravo Company, a few from Bushmaster. Just good ol' 20 and thirty rounders, with Magpul followers, .


I'll give you something to chew on....I used the Brownells 30 rd mags with the mil-spec green followers, they worked good....I changed the followers to mag-pul and started having problems....think about it, the round has less case taper than a .223....the cartridge stack is trying to straighten out a little....the mag-pul follower is trying to run perpendicular with the curve....the mil-spec greenies tilt with the angle of the cartridge stack....just about any 20 round straight works good.....being that there is less taper in the round they come off the feed lips pretty slick....the pmags are still my favorite...


Originally Posted By Bearbait1:
A 7.62x40 would feel right at home in the case.


Hopefully we will be able to help you with that you know how it is....things always seem to go slower than you would like...

'40'


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Link Posted: 6/17/2008 10:39:44 PM EST
[Last Edit: 6/17/2008 10:42:41 PM EST by 762x40mm]

Originally Posted By RooK:
How much of a 5.56 formed case do you need to trim off? Plan on doing any test with 240gr subsonics? I think that and 123gr supersonic deer hunting loads would be my intended use. If I ever get around to ordering a .300 barrel, I'll need to hook up with you for a recut chamber.


you only need to cut off about 5mm....just below the base of the neck...several ways you can do it....I use a small hobby lathe with a 3 jaw quick chuck....I can chuck-up a piece of brass and cut it in about 10 or 12 seconds...I like first forming with the Hornady sizer....then neck-sizing fire-formed brass with the Redding....thanks to the earlier post I'll see about some Hornady sets...I have tested up to 220 subsonics and they worked good....but it's really geard towards super-sonic

thanks for the interest...

'40'

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Link Posted: 6/18/2008 3:41:03 PM EST
Bearbait1 hits the nail on the head about the 6x45mm so I do not have much to add. For magazines I have been using CProducts Stainless Steel they let me seat bullets out to 2.295" and the extra .030 to .035" can help with some bullets ogive placement and the case mouth.

When looking at your 762x40mm wildcat I can see just how well this was thought out. Capable of sub and super sonic velocities, minimal bolt thrust issues, 30 cal. bullet selection. It all looks good to me I think you made a wise choice going with the 30 caliber.

Joe

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Link Posted: 6/18/2008 6:55:32 PM EST

Originally Posted By J-A-R:
I have been using CProducts Stainless Steel they let me seat bullets out to 2.295" and the extra .030 to .035" can help with some bullets ogive placement and the case mouth.



this is the kind of stuff I really like to see....thats what its all about....very useful information for someone with a 6x45mm....thanks for sharing...

40

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Link Posted: 6/19/2008 12:20:20 AM EST
Here's a list of dies from CH...anything look familiar?
30 - 221 Remington Improved 30 2 F $ 78.25 15 - -
30 - 221 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington 1 F $ 78.25 15 U
30 - 222 Remington Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington Magnum 1 F $ 78.25 15 U
30 - 222 Remington Magnum Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Magnum Improved 40 2 F $ 78.25 15 - -
30 - 223 Remington 1 F $ 78.25 15 U
30 - 223 Remington Improved 30 2 F $ 78.25 15 - -
30 - 223 Remington Improved 40

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Link Posted: 6/19/2008 5:19:31 AM EST
[Last Edit: 6/19/2008 5:31:45 AM EST by 762x40mm]

Originally Posted By JFA:
Here's a list of dies from CH...anything look familiar?
30 - 221 Remington Improved 30 2 F $ 78.25 15 - -
30 - 221 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington 1 F $ 78.25 15 U
30 - 222 Remington Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington Magnum 1 F $ 78.25 15 U
30 - 222 Remington Magnum Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Magnum Improved 40 2 F $ 78.25 15 - -
30 - 223 Remington 1 F $ 78.25 15 U
30 - 223 Remington Improved 30 2 F $ 78.25 15 - -
30 - 223 Remington Improved 40






yes...

30 / 221 = 300fireball, 300whisper, 300-221
30 / 222 = 300eagle
30 / 223 = 30/223ingram, 30/223apache


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Link Posted: 6/19/2008 12:32:16 PM EST
[Last Edit: 6/20/2008 2:55:40 PM EST by M4Madness]
Here you go:

We have Alloy barrels that have a bore diameter of .300-.301 and a groove diameter of .308-.309, These have been sold in the past to customers who intended to chamber for 7.62X39.

Please let me know if you have any other questions.

Regards,
Steven Pawl
General Manager
The Wilson Arms Company
203.488.7297
97-101 Leetes Island Rd.
Branford, CT 06405

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Link Posted: 6/19/2008 6:37:38 PM EST
[Last Edit: 6/19/2008 6:40:21 PM EST by uptown1]
height=8
Originally Posted By JFA:
Here's a list of dies from CH...anything look familiar?
30 - 221 Remington Improved 30 2 F $ 78.25 15 - -
30 - 221 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington 1 F $ 78.25 15 U
30 - 222 Remington Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Improved 40 2 F $ 78.25 15 - -
30 - 222 Remington Magnum 1 F $ 78.25 15 U
30 - 222 Remington Magnum Improved 30 2 F $ 78.25 15 - -
30 - 222 Remington Magnum Improved 40 2 F $ 78.25 15 - -
30 - 223 Remington 1 F $ 78.25 15 U
30 - 223 Remington Improved 30 2 F $ 78.25 15 - -
30 - 223 Remington Improved 40


All of the cartridges on this list "look familiar" to anyone that has done wild-cats with the .378 rim family of brass.....Am I missing something....anyone, anyone

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Link Posted: 6/20/2008 12:45:37 AM EST
[Last Edit: 6/20/2008 12:46:05 AM EST by moose01]
Have you been able to shoot the 7.62x40 out to 300 plus yards yet? What kind of velocity is it getting?

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Link Posted: 6/20/2008 6:16:40 AM EST
[Last Edit: 6/20/2008 1:38:39 PM EST by Zhukov]

Originally Posted By JFA:

We have Alloy barrels that have a bore diameter of .300-.301 and a groove diameter of .308-.309,

These have been sold in the past to customers who intended to chamber for 7.62X39.

Please let me know if you have any other questions.

The Wilson Arms Company


Wow! A barrel maker that sells a contoured blank!

What a concept!

And to think:


Originally Posted By JFA:

Originally Posted By bfarrin1:
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??



When you find an off the shelf, ready to go .308 groove 7.62x39 AR-15 barrel, let us know.


Until then, it would seem that you're trying to facilitate my "making whatever point I've dreamed up for you " that you seem to think I'm trying to make.

<Extraneous comments removed - Z>

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Link Posted: 6/20/2008 8:00:20 AM EST
[Last Edit: 6/20/2008 8:06:01 AM EST by 762x40mm]

Originally Posted By moose01:
Have you been able to shoot the 7.62x40 out to 300 plus yards yet? What kind of velocity is it getting?


Right at 300yds, a little more, is as far as I have tried it out.....uptown1 has a 600 yd range near where he lives at a friends house (how great would that be) and was going to put it through its paces.....following the intermediate cartridge concept the 40 was invisioned as being a 300yd cartridge....eventhough the ballistic calculator shows the 125 Nosler is going to hit at 600 yds with more energy than an average 115fmj 9mm pistol load does at the muzzle...about 200ftlbs more...

320pf and I have talked a couple times and at his suggestion I really would like to try the 135 Matchkings....he has produced some really good numbers with them in the 300/221 and the 40 should like them just as much....I should be able to try them out early in the week next week, no range this weekend, time to dust off the jet-skis and head to the river...hopefully uptown1 will have us some longer range numbers...

Thanks to bfarrin1, I am moving in the direction to have some dies made...now all we need is a source for brass and barrels and we will be good to go....

Thanks,

40

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Link Posted: 6/20/2008 8:15:41 AM EST
[Last Edit: 6/20/2008 11:28:58 AM EST 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?


I have a twist calculator that I built for the 300-221 and 40 in Excel....anyone that would like a copy send me a PM with your e-mail and I can send it to you....It uses a modified Greenhill formula for sub-sonic and super-sonic loads between 2,000 and 2,500 fps....the average velocity window for the 300-221 and the 40.....

You need to have Excel loaded on your computer for it to work....or if you don't have Excel send me the specs for your .308 bullet (length to the .001 and weight in grains and I can plug it in and post or send you a screen shot of the results..

40

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Link Posted: 6/20/2008 9:23:00 AM EST
[Last Edit: 6/20/2008 1:39:34 PM EST by Zhukov]
<No personal insults in the technical forums. Check your IM - Z>

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Link Posted: 6/20/2008 10:13:53 AM EST
[Last Edit: 6/20/2008 1:40:10 PM EST by Zhukov]
<Irrelevant comments removed - Z>

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Link Posted: 6/20/2008 12:16:29 PM EST
[Last Edit: 6/20/2008 1:40:30 PM EST by Zhukov]
<Irrelevant comments removed - Z>

bfarrin1.....thank you for the lead on the dies.....next week I will be sending over my info and payment to start work on (30) sets.....full length sizer and seater....

As for the other.....be like a duck.....don't give a quack....I don't....although the controversy has been keeping the thread at the top of the board....I guess there is a silver lining to every cloud (use your favorite noun in place of cloud)....

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Link Posted: 6/20/2008 3:44:59 PM EST
[Last Edit: 6/20/2008 3:48:43 PM EST by Parrandero]

Originally Posted 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.



www.brownells.com/aspx/NS/GunTech/faq.aspx?catid=13&faqid=991

: Ruger Mini-30 bore specifications.

A: This rifle is chambered for the 7.62 x 39mm cartridge. This cartridge, traditionally, uses a projectile with a nominal diameter of .311 to .312 inch.

At the time the Mini-30 was introduced very few bullet makers where producing .311/.312 inch bullets for reloading in the light 125-130 grain weight required. Ruger initiated the use of barrels with a groove dimension of .308 inch and a long tapered throat. The throat allowed the use of ammunition with .311/.312 projectiles by gradually squeezing them to the .308 diameter. In addition, ammunition loaded with more commonly available .308 diameter bullets could also be used.

Commencing in 1992 Ruger initiated a change to using .311/.312 nominal groove diameter, 1-10 inch right hand twist barrels in all Mini-30's. It was likely well into 1993 before all rifles coming of the production line incorporated the .311/.312 barrels.


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Link Posted: 6/20/2008 4:10:03 PM EST
Yes I've read that and reason too. Ruger said it was do to complaints about accuracy with the surplus ammo, not a pressure related thing.

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Link Posted: 6/20/2008 4:19:39 PM EST
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Link Posted: 6/20/2008 5:50:40 PM EST
Well maybe if the 7.62x39mm barrel mystery ever gets solved perhaps we can get back to the original topic. I hope you will still keep us updated as to the progress of your wildcat and when dies and barrels start to become available.

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Joe

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Link Posted: 6/20/2008 6:34:33 PM EST

Originally Posted By J-A-R:
Well maybe if the 7.62x39mm barrel mystery ever gets solved perhaps we can get back to the original topic. I hope you will still keep us updated as to the progress of your wildcat and when dies and barrels start to become available.

Thanks
Joe


I just finished putting the information and brass together for the die order.....was told six to eight weeks delivery....

I called Starline Brass today to find out about custom brass....they said a case in a case rim size that they don't currently make would not be economically practical

getting closer...

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Link Posted: 6/20/2008 6:52:42 PM EST
Not sure what economically possible means exactly, but I do know that way back in the 458 Socom infancy, we had a Starline group purchase and I believe the magic number was 25 thousand pieces to get them going. It was a bit of a headache for the organizer, but it eventually worked out. Just some food for thought.

Along the same lines, I guess I am a little confused about needing brass produced. Would this just be for the headstamp or possibly avoiding a fireforming step? Perhaps to deal with the shortening and neck relocation related to annealing? To be honest, I am using Lapua brass for my 6x45, and you would be hard pressed to find any better brass out there. Their consistency and care of construction related to the primer pocket and flash hole makes my heart go pitter patter every time I handle one

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