7.62x39 improved

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sub-sonic
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7.62x39 improved

Post by sub-sonic »

Image

to fix up a few feeding issues I had with my carcano conversion I decided to improve the 7.62x39 case to give it straighter sides so it would feed throught the carcano clips easier. works realy good

pictured is a standard case with a 230 grain lead. the improved case with a 230 grain lead. the improved case with a 147 grain and a cut away with the 147
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JohnInNH
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Post by JohnInNH »

how much more case capacity? 5-10 gr?

Did you leave any taper to aid in extraction?

Nice job.
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Post by sub-sonic »

I have only been loading trailboss in these. I can get .8grains more TB in the case but capacity was not the reason I did it.

I used a 6mmPPC reamer with a 30 cal pilot and ran it in until it cleaned out the original chamber. so the body is actualy longer than the PPC case
the neck is normal 7.62x39 length and the over all case length is the same as 7.62x39mm

I took a set of lee dies and modified the sizing die . so loading is no problem.

I am actualy thinking of doing this to my AR-15 but if it wont feed then its going to be costly. I tried a few in a standard mag and cycled them as best I could but they all ended up with bent sholders.
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Post by Smilodon »

Forgive me, but aren't lead bullets a bad idea throught centerfire suppressor? I plan on experimenting with 7.62x39 subs for my AK.
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Post by silencertalk »

The extreme taper of the 7.62x39 is part of the reason why it breaks bolts. There is additional bolt trust and it further stresses the AR bolt face. This will help that.
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Post by sub-sonic »

I am making another ar15 . a pistol this time. what I have planed on doing is using a standard 223 bolt head and turning the rim down on the
R-P brass to the size of the 223 rim.
Smilodon wrote:Forgive me, but aren't lead bullets a bad idea throught centerfire suppressor? I plan on experimenting with 7.62x39 subs for my AK.
so I have been told. still I have shot over 1000 cast lead bullets through my home made silencer and the only problem I have had so far is powder fouling.
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Post by durtak »

sub-sonic
still I have shot over 1000 cast lead bullets through my home made silencer and the only problem I have had so far is powder fouling.[/quote][/quote]

Do you use gas check on the cast bullets?
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Post by silencertalk »

I would change the taper to what a 5.56mm has so it is still reliable extraction.
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Post by dbooksta »

I don't understand what was done here: Did you ream out your chamber to make it straighter and then fire-form that brass?
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Post by sub-sonic »

dbooksta wrote:I don't understand what was done here: Did you ream out your chamber to make it straighter and then fire-form that brass?
Yes
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Post by blkexp98 »

Ive never gotten that deep into reloading but i read you reamed your chamber and use fireformed brass. Do you just use a neck sizing die instead of a reamed out full length? Ive wondered what you could do with a tweaked 7.62x39 case with a .308 bore barrel so you have some better bullet choices.

Looks like you know what your doing so good work and keep us posted how it works.

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Post by clay_breaker »

I have been thinking about doing just that. 7.62x39 action with .308 1/8 twist bbl. I want to spin those 240 gr subs. But then the question becomes, if one is going to re-barrel a rifle, should you just get a .223 rifle and make a 300 whisper.
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Post by dbooksta »

clay_breaker wrote:I have been thinking about doing just that. 7.62x39 action with .308 1/8 twist bbl. I want to spin those 240 gr subs. But then the question becomes, if one is going to re-barrel a rifle, should you just get a .223 rifle and make a 300 whisper.
Only if you don't mind the hassle of cutting and forming your own brass! Also if you go 7.62x39mm even with a .308 bore you can still (at least according to Peter Cronhelm) shoot the cheap .311 factory bullets when you want to.
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Post by JohnInNH »

dbooksta wrote:
clay_breaker wrote:I have been thinking about doing just that. 7.62x39 action with .308 1/8 twist bbl. I want to spin those 240 gr subs. But then the question becomes, if one is going to re-barrel a rifle, should you just get a .223 rifle and make a 300 whisper.
Only if you don't mind the hassle of cutting and forming your own brass! Also if you go 7.62x39mm even with a .308 bore you can still (at least according to Peter Cronhelm) shoot the cheap .311 factory bullets when you want to.
In Peter's article it again recommends loading boat-tail bullets backwards.
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Post by whiterussian1974 »

Smilodon wrote:Forgive me, but aren't lead bullets a bad idea throught centerfire suppressor? I plan on experimenting with 7.62x39 subs for my AK.
The Antimony content hardens the Lead while reducing friction, preventing baffle spatter.
.22lr rounds use less Antimony because of cost. They use dry lubricant instead.

https://en.wikipedia.org/wiki/Antimony# ... on_volumes
Antimony production in 2010:
People's Republic of China: 120,000 tonnes @ 88.9% of world production.

The abundance of antimony in the Earth's crust is estimated at 0.2 to 0.5 parts per million, comparable to thallium at 0.5 parts per million and silver at 0.07 ppm.
So it's roughly 3 times more prevalent than Silver, but China corners the market in production.
This is the map of Lead Production:
https://upload.wikimedia.org/wikipedia/ ... posits.svg
This is one reason why .22lr is so cheap. The enormous demand also means a steady supply. Kind of like the price of Salt vs. Steak.
Last edited by whiterussian1974 on Sat Oct 12, 2013 10:24 pm, edited 1 time in total.
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Re:

Post by whiterussian1974 »

JohnInNH wrote:
dbooksta wrote: Only if you don't mind the hassle of cutting and forming your own brass! Also if you go 7.62x39mm even with a .308 bore you can still (at least according to Peter Cronhelm) shoot the cheap .311 factory bullets when you want to.
In Peter's article it again recommends loading boat-tail bullets backwards.
If you use .311 slugs in a .308 barrel you need to watch pressure. If you use a slower powder, no problem. Over time, the .308 will erode to .310. I would rather hardcast my own heavy .311 slugs. Loading boattails backward has been used with some success, but boattail SemiWadcutter hollowpoints are more stable.
Have you thought about 9x39mm? A .358 subsonic slug. If Hardened Steel Insert, can penetrate 10mm of steel armor. Lethal Effective Range: 400m.
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Re: 7.62x39 improved

Post by dbooksta »

Yeah, I need to amend that: Putting Russian bimetal .311 bullets through a .308 bore makes a huge mess -- it shreads the jackets, fouls everything with copper alloy, and seems to result in terrible accuracy if not in-flight disintegration (don't know how else to explain missing cardboard at 50 yards, but the hot metal splattering out the gas port and muzzle is certainly unpleasant enough!).
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Re: 7.62x39 improved

Post by whiterussian1974 »

A ribbed, low drag, low fraction .308 design.
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Re: 7.62x39 improved

Post by IvanJ »

I am very interested in this improved cartridge. I shoot a Ruger Mini 30 7.62x39 and I am considering reaming the chamber partly as a solution for magazine troubles. I'm guessing that these cases will work in a Mini 14 mag, the sides being less tapered. Mini 30 mags is a problem here in South Africa. Also improved ballistics will be good. I'm sure the action could handle it being a 586 Series. Any advice is welcome.
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Re: 7.62x39 improved

Post by ohnomrbillk »

Many years ago, my friend came up with the covert line of cartridges when the 6.5 grendel was still a wildcat.

For all practical purposes, his 30 covert is a 30 Grendel.

It does everything you described for purpose above.

The advantage of his is the ability to use modified off the shelf reloading dies.
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Re: 7.62x39 improved

Post by IvanJ »

What bullet speeds are you getting?
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