7.62x39 uppers

Anyone have any experience with them ?

I just bought one lol never shot it yet though

I have not had any serious problems with my 762x39 uppers, but there are some things to consider. Magazines are the main issue. The mags can be more expensive and some of them are more reliable than others. 762x39 performs best in a curved magazine as used on the ak. You will pay more for the 762x39 ar mags than the 556 mags.

The mutant ar in 762x39 addresses the mag and bolt reliability issues but it is a different system.

Over all I am happy with my 762 uppers. I have hand loaded both the 762 and the 300 BO. I prefer the 762 since it is a much more forgiving cartridge.       

Yeah Omni, rub it in. 

Thanks for the info AstroB.

Any particular brand mags you'd recommend ?

I prefer the asc or c products mags. The 20 and 30 round mags seem to be getting scarce.

Couple of friends have.i guess once you find out which mags work with your gun it's all good.Mine just came in the mail today

Damn ! Nice J !

I just ordered mine from PSA
http://palmettostatearmory.com/psa-pa47-16-midlength-7-62x39mm-1-10-nitride-upper-with-bcg-and-ch.html

Not sure how the mid-length gas will work but what the heck.

i've put together several 7.62x39 AR-15's.  i especially like the cheap ammo prices, in comparison to store-bought 5.56 ammo.

the $100 Anderson Arms 16" barrels sold by Primary Arms are pretty good for the money, HBAR  profile, carbine gas-length, parkerized.  used with H3 buffer.  i trust only the AIM BCGs, although frequently out-of-stock, have used the black phosphate, nitride, and NiB.  they work equally well, nitride & NiB is a little easier to clean, and the cheap russian ammo is dirty.  sent one of these barrels out to AR15barrrels (CA) and had him shorten, pin, weld to 14.5" with a muzzle brake.  it's fun to shoot and pretty darn accurate also.  better than my 14.5" 5.56 shooting the cheap store-bought mil-spec 55gr ammo for sure.

i've also assembled a 7.62x39 AR using the 16" Faxon barrel (mid-length gas), with an Adams Arms piston conversion kit.  took some experimentation getting the gas port size dialed in due to the piston conversion, but in the end, now it runs like a swiss watch.  runs a lot cleaner internally also.  will probably have that chopped-pinned-welded to 14.5" also.  and also building a normal direct-impingement version (Faxon middie, 16 chopped to 14.5, etc), waiting for the barrel to come back from the chop shop.

i've used the cheapest mil-spec stripped uppers i can find, usually in the $50 range, Anderson Mfg, no problems at all.

have used both CPD and ASC mags, 10rd, 20rd & 30rds.  the internet forums favor the CPD mags by far, they work as-is.  i'm starting to lean towards the ASC mags but use a small honing stone to smooth the edges of the curved feed lips, knock off the sharp edge left by the the stamping, sheared process, help the cartridge slide out of the mag smoothly, and tip up onto the M4 feed ramps, just my own OCD.  anways, these slightly-romanced ASC mags do provide reliable uneventful feeding.

i've gotten into the habit of polishing the feed ramps of all AR barrels that i assemble (reduces scoring marks on the brass, smoother feed), not sure if that helps in the guiding of the steel case 7.62x39 cartridge out of the mag, up the ramp and into the chamber.  FWIW.

Good info rp thanks !

Is the heavier buffer better for the 7.62x39 ?

buffer weight is dependent upon several things:  caliber, barrel length, gas length, gas port dia, buffer spring, ammo type, etc.  but in real world, usually determined by trial and error.  my understanding is that it's best (least wear and tear) to run the heaviest buffer that will still ensure reliable cycling of the action.  i.e.: with 1 round in the mag, does the bolt hold-open (lock back, engage the bolt catch) on mag-empty.  start off with a light buffer, e.g. 3oz, shoot the 1 rd, make sure the bolt holds open on mag empty, and step up incrementally until the BCG does not cycle back sufficiently to snag the bolt catch.  then back the buffer weight down 1 step.

same type of trial-and-error process as with an adjustable gas block.

the 7.62x39 does pack a little more energy than the 5.56 and you're trying to absorb the recoil.

the reason i mentioned the H3 is that i've found that with the 16" Anderson Mfg 7.62x39 carbine-gas barrel from Primary Arms, that config works fine with H3, reliable, dependable, time after time, even with the barrel chopped to 14.5.  so perhaps i should try a buffer that's 1 step heavier than H3 (5.4oz), but it don't have one, so H3 it is.  maybe i need the H3 bfr with an adjustable gas block?  hmmm.

with a different mfr's barrel, it'd be a new experiment..

+1 on rpol98 responses.

I polish my feed ramps as well. On my ballistic advantage barrel I had to widen my ramps and Dremel a bit in the upper receiver to make it smooth. I run 5.4 oz buffer on that and it shoots fiocchi and American eagle x39 ammo. Cycles and feed as good as a 5.56. I run LMT (aermet 100 steel/nib) and Cason manufacturing (17-4 steel/ nib) bolts. The problem in the past was manufacturers were milling out 5.56 bolts to fit x39 ammo. Nowadays they are making it from scratch so it's stronger. Also dependent on type of steel being used too. AIM surplus bolts nitride finish adds integrity to the steel as well as Nickel boron (nib). Heard good things bout them but I just stuck to what I know works but paid 2 arms and a leg for it.

I too have faxon barrel . The flame fluted one. Never got to shoot this one yet. But Im using a 4.8 oz buffer first to check function and if it works I'll drop in a 5.1oz and check with that as well.

Gas port placement and diameter plays a huge role in what buffer weight to use. Mine are both mid length gas systems. BA barrel has a .098" gas port diam. And the faxon has .096" gas port diam. this is the selling point on the barrels for me.

I also only use ASC mags. Works as long as you smooth the top-front of body of magazine. ASC stamping or bending or whatever sucks so every mag I had was failing til I dremeled about 1/8" inch off then filed it smoothed. Runs fine and soft points are gtg.

BTW my BA 7.62x39 ar15 shoots softer than my friends 5.56 and 300 blk out. infact it shoots softer than my old ar6951 (colt 9mm). And that is why my gf took this rifle for herself. Without scope the rifle weighs 6 lbs 3 oz. using irons (Troy 45 degree) I got a 3 inch group  at 100 yards. ( never tried with scope yet ).havent had a ftf,fte, jam etc yet. But I use brass ammo. Berdan stuff would make it a pain to clean on DI ar15. So kudos to RPOL for doing a piston system lol.

18" KAK 7.62x39 Value-Line barrel:
assembled an upper using this barrel, mid-length gas.  i guess the gas port is a little big, was still violent recoil with the H3 buffer (5.4oz), didn't have anything heavier at that time, so added an SLR adjustable gas block, now it cycles nicely with a Spikes T2 buffer (4.1oz).  it was shooting pretty nicely at 200yds (Wolf cheap ammo), now i just gotta work on my own skills and dial in the scope.

my formerly 16", now 14.5" Faxon Adams Arms piston conversion 7.62x39 barrel should be back from the chop shop in the next week or so.  should be fun.

I have a Hardened Arms 16inch upper on mine. It came with the extended firing pin for those tougher primers on some 7.62x39. I installed a Spikes heavy buffer and spring and so far have had zero issues. I also hand load so I've shot mostly brass but the 100-200 rounds of steel have shot flawlessly as well.

i finally finished my Adams Arms piston conversion on a 14.5" Faxon 7.62x39 mid-gas-length barrel.  The barrel was originally 16" and i had a gunsmith shorten it to 14.5" and pin, weld the muzzle device.  i ended up drilling the gas port to 9/64", and also had to drill out the AA gas plug to 9/64" (originally 1/8"), and now have reliable action with the desired 4.1oz buffer, and reliable LRBHO. standard M4 buffer spring, Wolf 123gr FMJ steel case.

i just hope the political sanctions don't impact availability of cheap Wolf steel case ammo

hindsight:  although the Faxon barrel is chambered for 7.62x39, the groove diameter is .308 with a 1:8 twist.  designed for the hand-loader for heavier hunting rounds.  if i had to do it all over again, i would've started off with a mid-gas barrel that had a true .310 or .311 groove diameter and something closer to the Kalashnikov 1:9.5 twist, which is presumably optimized for cheap COMBLOC ammo. 16" or longer, doesn't matter, since i was getting it chopped anyways.  although Gorilla Machining has a 14.5 mid-gas 7.62x39, not sure if i'm sold on their non-M4 feed-ramp style for the AR application.

ETA: 2/2/2018
everything was fine & dandy, until I went and bought another case of Wolf ammo, same type as before.  I guess the Russia sanctions must've impacted the Wolf ammo plant, 'cuz they went a little stingy on the powder.  This upper, that was sorted out fine with the earlier batch of Wolf, now wouldn't cycle, even after switching to my lightest 3.0oz buffer.  I had some of the earlier batch of ammo left over, tried that, and it worked fine again.  Well, there's some discussion here-and-there, about the 7.62x39 cartridge having a quicker pressure drop off than the 5.56, which makes it more susceptible to short dwell times, more so than 5.56.  Sort of like the same discussion about the 5.56 "Dissipator", 16" barrel with rifle-gas length, very sensitive to ammo.  So, in the future, for 7.62x39 piston build, I'm gonna stick with the carbine gas length for 14.5" (pinned & welded to 16.1" legal).  However, on this upper (mid-gas 14.5 piston), I could hammer out the pins on the gas block and drill the gas port out to 12%-20% larger cross sectional area, and then use the buffer weights to tune for ammo variance.  Or, I could start over with lessons learned, and build the 7.62x39 14.5" piston with carbine gas length.

I gotta give a lot of credit to that guy Kalashnikov for his design of the AK47.  Not sure how it works so battlefield reliably, with the gas port way up there near the muzzle, piston.  They must have a humongous gas port.  wonder what the bolt weight comparison is, although it'd be difficult for any comparison, because totally different design, recoil spring, etc.

Aieahound.  Just saw an unbelievable stainless barrel version of the 7.62 upper at Dexters with a set trigger.  The break is unreal crspy.  He says a customer of his printed a 4 inch group at 600 yards with Lapua.  If that's anywhere true I have been looking in the wrong place for the last 15 years!

I have built many.  I would recommend to disassemble the hardener arms and reassemble it.  I use usgi mags and modify the 30 rounders for 20 rounds.  There is a lot of tricks for these and hard to go into detail.

Aieahound.  Just saw an unbelievable stainless barrel version of the 7.62 upper at Dexters with a set trigger.  The break is unreal crspy.  He says a customer of his printed a 4 inch group at 600 yards with Lapua.  If that's anywhere true I have been looking in the wrong place for the last 15 years!

I got 5/8" 5 shot groups with lapua ammo damn stuff cost $1.60 a round now. Also get the same with reloads.  Mine is a SS 18" barrel.  Yup 4" at 600 yards!

My 16" barrels get 7/8" grouping with reloads or lapua.  With Muzzle Brake. 1.25" groups with silver bear

Radical Firearms 7.62x39 upper on a Spike's lower
had to do a few things to work properly

Just curious.  Are these for pig hunting?

(ammo is cheaper than 300 bo)