[Pop quiz]

So it sounds like 9.5” in x39 is money with the RA barrel availabilty? Maybe lobbing shots at 250/300 yards but completely effective within 200 yrds?

 

[Northern]

@Pop quiz I only recently got my 9.5” x39 barrel and have not had much outdoor range time with it, so I cannot speak to the distances. I’m looking forward to giving it a workout all summer.

 

[roflcopters]

If you want steel case like 8m3 or SSTs to expand, min. 12." 154gr sp will not expand under 16"
If you have a can and just want a blaster, 9.5 is ok. It'll cycle the subsonic steel case on setting 7 (the 200gr stuff that isn't supposed to cycle semi auto). If you don't have a can, the muzzle blast is kind of ridiculous.

 

[Snag]

Everyone seems to want a short barrel 7.62x39.
If that's the case then switch to 300 Blackout.
It's designed for 8" - 10" barrels and packs a better punch than the 7.62x39. Also you get less flash out the muzzle, easier to suppressor, and is a much better choice.
As for the 7.62x39 I would recommend a 16" - 20" barrel so you burn all your powder and get less flash. A short barrel 7.62x39 is like a short barrel 5.56. These rounds are not designed for a short barrel and an AR is not really designed for those two in SB form.
However the 300 Blackout and a short barrel AR are a match made in heaven.

 

[Sean K.]

Everyone seems to want a short barrel 7.62x39.
If that's the case then switch to 300 Blackout.
It's designed for 8" - 10" barrels and packs a better punch than the 7.62x39. Also you get less flash out the muzzle, easier to suppressor, and is a much better choice.
As for the 7.62x39 I would recommend a 16" - 20" barrel so you burn all your powder and get less flash. A short barrel 7.62x39 is like a short barrel 5.56. These rounds are not designed for a short barrel and an AR is not really designed for those two in SB form.
However the 300 Blackout and a short barrel AR are a match made in heaven.

7.62x39 loses very little with each inch of bbl removed....and the supersonic ballistics are similar to 300 BLK on paper even in short bbls. In the real world, X39 hits steel a LOT harder than 300 BLK. I have XCRs in both x39 and 300 with 9.5" bbls.

300 shines at suppression....and that's its real niche.

 

[Bret]

Plus, 7.62x39 is significantly less expensive and more broadly available.

 

[Northern]

Plus, 7.62x39 is significantly less expensive and more broadly available.

Absolutely. Add a good blast shield and gtg.

 

[etr654]

ideal barrel length for 7.62x39

Old thread, but the information can still be of help to anyone else..

Depends what the goal of the rifle is. For an all-purpose rifle, 12.5" seems to be the sweet spot for 7.62x39. It loses little velocity (certainly not enough to bring it below the velocity threshold of modern defensive ammo) and as such can do everything the 16" carbines can, but have better balance and handling. Adding a can brings you out to normal carbine length instead of out to musket length.

If you're going for a PDW style weapon, I would emulate the 8.5" Arsenal krink's front end with the folding stock of your choice. You'll still get useful velocities out of the 8.5" barrel (most of the powder in most loads has already burned by then), even if your effective range is less than that of the 12.5" and longer barrels.