Optimum barrel length for 7.62x39?

[DMK]

Has anybody ever clocked the velocity difference between a 20" SKS and a 16" AK with 7.62x39?

It's my understanding that the 24" RPK only gains about 50fps over the AK. I'm wondering how the 20" SKS barrel compares to the AK. Especially considering that it was the rifle that the 7.62x39 round was first used with.

I suppose it should fall in about 25fps faster but you never know. The round wasn't really designed for long barrels. The powder could have burned out and drag could have slowed the bullet down in that 24" RPK barrel. It is feasable that it could be faster in the SKS than in the RPK.

 

[NMshooter]

Most accurate 7.62x39 rifle I ever shot was a Bulgarian SLR-95.

About 2 MOA close in, no more than 3 out to 600 with Wolf FMJ.

16" barrel should be plenty so long as it is a quality barrel in a good action.

Longer barrels in this caliber do not appear to have any significant differences in muzzle velocity.

I think you would have to load your own ammo with different powder to get more out of a longer barrel.

Not a bad cartridge, though you really have to hold over shooting at a distance. Wind drift is similar to .223.

 

[natedog]

I've noticed that my Para SKS has more muzzle flash and blast than a 20" SKS- the fireball is noticable, even in broad daylight. Not very scientific, I know, but hope it helps. Myself, I wouldn't worry too much about lower velocities from shorter barrels. It's still making a 1/3" or 1/4" hole (7.62 vs 5.56), probably tumbling and or fragmenting, and if you put that through a major blood vessel, CNS, etc., the target will not live for much longer.

 

[DMK]

Yea, I already have a 16" SKS, an AK and numerous 20" SKS. I realize that accuracy is not dependant on barrel length. Too many other variables on these guns.

I was just curious about the velocity difference. I don't have access to a chrono.

I guess nobody here's ever clocked 'em or seen a chart somewhere on the 'net?

 

[NMshooter]

It has been a while since I played with this cartridge, so I no longer have any hard data.

I think you can get higher muzzle velocity out of the longer barrels if you reload, but I am fairly certain that typical milspec ammo does not gain much out of an SKS or RPK length barrel.

Admittedly I may be wrong.

I do not recall any specific information, but you may try the AK section of ar15.com, they might have more.

Sorry about that.