300 AAC vs 7.62x39 AR upper for suppressed subsonic

[ironworkerwill]

I know this pops up from time to time, but a friend an I are trying to get ideas.
1)Mostly it's an issue of 'will the 7.62 be as effictive as the Blackout' as far as their ability to cycle subsonic.

2)Does either round have an edge in accuracy? (Both having proper twists)

3)Would a reloader rather load one over the other as far as components and the ability to run subsonic?

4) Is the modern 7.62X39 barrel .308, .310, .311....ect?

 

[LiveLife]

I considered getting a 7.62x39 AR upper when I was putting together my .300 BLK rifle.

For me, the deciding factor was not particular to accuracy but the greater availability of .308 projectiles and .223/5.56 cases to convert them to .300 BLK cases. Since I already reload .223/5.56, I didn't need to purchase additional brass and I think getting a hold of "reloadable" 7.62x39 brass is more challenging.

I don't think many get 7.62x39 AR uppers to shoot reloads but rather to shoot cheaper bulk steel case ammo.

As to subsonic loads that will reliably cycle the gas system, I think .300 BLK wins hands down as there are many established 230+ gr lead loads using A1680, H4227, etc. that have proven to cycle the pistol gas tube length 16" .300 BLK uppers and lock the bolt back on the last round.

If you consider powder coated lead .300 BLK bullets, you won't even have to worry about fouling up the gas tube with lead and have the flexibility to load subsonic or supersonic without leading the barrel.

FYI, Missouri Bullet Company started offering Hi-Tek coated lead bullets and they also offer coated .300 BLK bullets - http://www.missouribullet.com/results.php?pageNum_rsCWResults=1&category=6

 

[ironworkerwill]

Well stated!

I'd thought of using 5.56 brass for the 300 and possibly lapua or ppu brass for 7.62x39. Boxer primed brass cases are sometimes hard to find in 7.62x39.

We just orders a few lowers from PSA and my friend mentioned one of the lowers will be a 300blk so it could be used for varmints. We entertained the idea of the Russian round, however, I believe the 300 blk may suit the needs.

Thanks

 

[Mr.Revolverguy]

Here is a 300 Blackout page with a lot of data, pictures and reloading info on it. Of course we all know how that goes use all safety precautions.

http://www.dayattherange.com/?page_id=3460
http://www.dayattherange.com/?page_id=3807
http://www.dayattherange.com/?page_id=3812
http://www.dayattherange.com/?page_id=3817

Should help you get an idea of what the 300 is capable of.

 

[ironworkerwill]

That's a good read. Thank you sir.

 

[mstreddy]

Iron, another thing to consider is the ready availability of AR mags for 300 Blackout. -- Standard AR mags. This is not the case for 7.62x39 for the AR. There are some weak ones and the better ones are a little pricey compared to AR mags.

 

[JohnSkiS]

My vote is for the 300blk. I have readily drank the AAC Kool aid. I don't know if this is against the rules, but check out 300blktalk.com for a ton of info on the cartridge. Forum just like this one, but 300blk specific. If I want to shoot 7.62x39 I use my SKS or my AK. But I would say, that of all the "weird rounds" for the AR, 300blk is the best.

 

[ironworkerwill]

In lieu of the bore size, reloadable brass, 1/10 Russian twist, and mags we have chosen the 300 AAC. Thank you all.