7.62x39 to 7.62x51?

mrbeil

mrbeil

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I was having a debate with a buddy of mine, and it boils to whether it is possible to convert a rifle designed for 7.62x39 like an AK or SKS to the 7.62x51 NATO round. Would the action of said rifles even be able to handle it?
 
Anything is possible, for a price. Your SKS or AK will need some major mods to accommodate the longer case.

Keep in mind you'd have to re-barrel, not just re-chamber.
7.62x51 = .308
7.62x39 = .311
 
9x19p said:
Anything is possible, for a price. Your SKS or AK will need some major mods to accommodate the longer case.

Keep in mind you'd have to re-barrel, not just re-chamber.
7.62x51 = .308
7.62x39 = .311
Click to expand...

You can simply re-chamber. You'll likely get poor performance, but no harm will come. HOWEVER, AKs and SKSs were neither designed nor proofed for .308/7.62 NATO. Such an endeavor would be foolhardy and dangerous to perform on a SKS or AK action.
 
It's not something I'm even contemplating doing as it is way too out there in terms of what I'm comfortable doing. I was arguing that the action wouldn't be strong enough
 
mrbeil said:
It's not something I'm even contemplating doing as it is way too out there in terms of what I'm comfortable doing. I was arguing that the action wouldn't be strong enough
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It's strong enough. It's actually overbuilt for the 7.62x39 cartridge.

The SKS-45 is a scaled down SHS-14 automatic sniper rifle.

2002070703.jpg


And the PTRS-41 is a scaled up SHS-14
 
BeaverMeat said:
It's strong enough. It's actually overbuilt for the 7.62x39 cartridge.

The SKS-45 is a scaled down SHS-14 automatic sniper rifle.

2002070703.jpg


And the PTRS-41 is a scaled up SHS-14
Click to expand...

Im not sure it would be strong enough. The increased pressure would cause cycling to be very hard. Mind you there would be a drop in pressure as well from the undersized bullet.

I still cant see it being a good idea to try.....
 
antiqueguy said:
never heard of a SHS 14 but the PTRS is the sks's big brother
Click to expand...

It's actually SVS-14... Translate error.

Source: http://www.bratishka.ru/archiv/2002/7/2002_7_7.php


Aries- said:
Im not sure it would be strong enough. The increased pressure would cause cycling to be very hard. Mind you there would be a drop in pressure as well from the undersized bullet.

I still cant see it being a good idea to try.....
Click to expand...

The gas system would have to be modified obviously. One could reload a x39 case to 7.62NATO pressures and give it a go. Safely of course.
 
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BeaverMeat said:
It's actually SVS-14... Translate error.

Source: http://www.bratishka.ru/archiv/2002/7/2002_7_7.php




The gas system would have to be modified obviously. One could reload a x39 case to 7.62NATO pressures and give it a go. Safely of course.
Click to expand...

I suppose if one was so inclined, one could load a x39 case the 7.62NATO pressure and take out the gas piston on the sks in order to test this, however, I wouldn't want to be within 100 meters of that thing going off
 
mrbeil said:
I suppose if one was so inclined, one could load a x39 case the 7.62NATO pressure and take out the gas piston on the sks in order to test this, however, I wouldn't want to be within 100 meters of that thing going off
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SAAMI max pressure for the 7.2x39 is 45,000 psi. Max pressure for the 7.62x51 is about 60,200 psi. The SKS may be overbuilt for 7.62x39 but that's a pretty significant difference. Think I'll keep my face away from that conversion. G:
 
ted_dent said:
SAAMI max pressure for the 7.2x39 is 45,000 psi. Max pressure for the 7.62x51 is about 60,200 psi. The SKS may be overbuilt for 7.62x39 but that's a pretty significant difference. Think I'll keep my face away from that conversion. G:
Click to expand...

The OP said 7.62x51 which is rated at 50,000 psi. 7.62x51 is not the same as .308 don't forget. the SKS can take the pressure considering the absolute maximum x39 pressure is 49,000 psi... It's on the verge of destruction.

The real question is the AK actions stronger then the SKS action? AK's actions have been chambered in 7.62x54r, 7.62x51, .243, .308, 30-06, and 8x57(8mm Mauser) with no modifications to the action itself.

Edit: The Yugo M76 in 8x57 has a reinforced action. (Damn, I want one of those)

The rest like the RPK, PSLs, M78s use the original action design.
 
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No harm will come, except for when the 50 plus thousand pound pressure of the .308 blows the 40ish thousand pound pressure 7.62 x 39 receiver apart and kills or severely maims the shooter. Doesn't matter because the .308 case is longer than a loaded 7.62 x 39 cartridge so it's receiver will not work with it.
The 7.62 Galil was designed from the ground up for that cartridge.
In any case, "7.62mm" has nothing to do with the cartridge or bullet. That's the nominal bore diameter only.
 
The SKS uses a tipping bolt, rear locking action. Just as the AG42B, FN 1949 and FN FAL do.
Would the SKS action safely hold a 7.62x51 round?
Doesn't matter, given that the x51 cartridge is some half inch longer than the x39 cartridge. Not a conversion worth considering.
The basic AK design has been scaled for the x51. The SKS could be as well.
But converting either is a non-starter.
As far as handloading a x39 to x51 pressure goes, the difference in casehead diameter is going to affect backthrust, so pressure alone isn't going to prove much.
The SKS rifle obviously withstands the pressures of x39 proof rounds, so it is obvious that it will not fail with higher pressure loads than x39 service ammunition.
 
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