So what's the good and bad about 7.62x39 AR15 uppers?
- Thread starter randyhub
- Start date
I am looking to get one but I want a 10" barrel. I know it will bark pretty good but its just for fun so why not. Other than the cheaper surplus ammo I don't think there is much of an advantage. That being said, with the price of ammo going up it won't be much of a deal for long.
The two things i dont particularly like about the 7.62x39 ar is the bolt face has to be bored out and is inherently weaker. Some companies make stronger bolts and as of now i have yet to break mine ( i bought a back up). The other issue is weak primer strikes on surplus ammo i fixed this problem by turning the shoulder down on the firing pin. In the end of the day i almost never shot that upper if im shooting a ar its 223.
maple_leaf_eh
CGN Ultra frequent flyer
Be careful using the name of that "M" gun company in Eastern Ontario. They pi$$ed in the pickles a few years back and got banned from CGN, despite being a major sponsor.
The problems I know about are directly related to the cartridge. It needs a curved magazine when the AR is straight up right (and arguably all mags feed on an angle, but let's not go there), so feeding and other reliability issues will always be a problem. Secondly, will be the recoil impulse and the gassing. A standard 5.56 round is not the same as a 7.62x39. Finally, I'd be concerned about the buffer weight. Most shooters never think about it, but the bounce from the buffer is a closely balanced force in the operating cycle.
The problems I know about are directly related to the cartridge. It needs a curved magazine when the AR is straight up right (and arguably all mags feed on an angle, but let's not go there), so feeding and other reliability issues will always be a problem. Secondly, will be the recoil impulse and the gassing. A standard 5.56 round is not the same as a 7.62x39. Finally, I'd be concerned about the buffer weight. Most shooters never think about it, but the bounce from the buffer is a closely balanced force in the operating cycle.
7.62x39 does not always feed well from an AR magazine regardless of what follower is in it. Lots of guys have had poor reliability feeding from XCR-L x39 pistol mags. X39 needs a magazine curved like an AK magazine to feed reliably, when it's only 5 rounds the modified AR magazine usually works but more than that is a 50/50 chance there will be problems.
Other than that I just don't like converting US designed rifles to shoot Russian surplus ammo, For me, if I want to shoot x39 I want a rifle that was designed from the ground up for that cartridge. That way the chances of it being reliable are the highest.
If you want to shoot x39 I would buy a Type-81, the one I had was a lot of fun and was very reliable.
Other than that I just don't like converting US designed rifles to shoot Russian surplus ammo, For me, if I want to shoot x39 I want a rifle that was designed from the ground up for that cartridge. That way the chances of it being reliable are the highest.
If you want to shoot x39 I would buy a Type-81, the one I had was a lot of fun and was very reliable.
One other thing nobody has touched on, but was pointed out to me by Shawn at ATRS. I was thinking of doing a 7.62X39 in my sporter. These are a DI gun, and if you are shooting corrosive, you're actually putting the gases (with corrosive components) back into the bolt, and action of the gun. AK's, SKS's, 858's, and Type 81's, which are made to shoot 7.62X39 are all piston guns, and as a result, limit the exposure to the corrosive gasses.
I bought one of the Marstar uppers...16" barrel, so it can go to the States with me, someday.
It has run very reliably for me, just keep it 'wet'...ie. well lubed. I use the 10-round pistol mags with it...no issues whatever. Of course, I can't speak to the large curved magazines, but I suspect they need to be deburred and lubed as well to be reliable. A LGS has some reasonably cheap non-corrosive commercial ammo, and I have a Bushnell AR Optic for 300 Blackout to go with it...so I'll be testing for accuracy RSN.
As for weaknesses.... A spare bolt might not be a bad idea, but I'm not sure the stresses on the bolt face are that great. As for shooting corrosive ammo...IMO an AR upper is more corrosion resistant, and easier to wash out than an SKS. I haven't shot mine a lot, so time will tell, I guess.
It has run very reliably for me, just keep it 'wet'...ie. well lubed. I use the 10-round pistol mags with it...no issues whatever. Of course, I can't speak to the large curved magazines, but I suspect they need to be deburred and lubed as well to be reliable. A LGS has some reasonably cheap non-corrosive commercial ammo, and I have a Bushnell AR Optic for 300 Blackout to go with it...so I'll be testing for accuracy RSN.
As for weaknesses.... A spare bolt might not be a bad idea, but I'm not sure the stresses on the bolt face are that great. As for shooting corrosive ammo...IMO an AR upper is more corrosion resistant, and easier to wash out than an SKS. I haven't shot mine a lot, so time will tell, I guess.
I've got one with a 14.5" barrel. Runs pretty reliably aside from a weak extractor spring that I haven't gotten around to swapping.
There were "enhanced" firing pins going around which protrude noticeably more through the bolt face. Helps with any hard primers.
There were "enhanced" firing pins going around which protrude noticeably more through the bolt face. Helps with any hard primers.
I built a Sporter in 7.62x39 and have no plans of running corrosive through it for this very reason. I don't mind cleaning my guns but don't want to have to do it every time I bring it home. All I've ran through it is Hornady Black 123 gr SST.
It's a 19" IBI barrel with a mid length gas system, a JP Enterprises SCS buffer system and a Brownells Nitrided BCG. I had 1 mag that needed the feed lips bent upwards at the front because when it was full it was too tight for the first round to feed reliably. After the little tweak it's been good to go. The other mag I used worked fine. Since this picture I replaced the Trigger Tech Adjustable with a Timney as I had half a dozen light strikes with the TT. No issues with the Timney.
If you want to build a Sporter in x39 go for it. There is still budget friendly ammo that is non corrosive. Only thing is you will most likely need to use a trigger with a heavier hammer spring if using cheaper ammo.
* I know this isn't an AR as per the OP's topic of discussion but it's close enough that I thought it to still be relevant.
Advantages? First, with the aluminum, stainless, chrome-lining, and assorted hi tech coatings, what is there to rust in an AR, especially if you keep it lubricated?
I oil mine with Ballistol (because it compounds with water), and cleanup involves running hot water into the upper, stripping and rinsing the BCG, and oiling as normal. Fastest thing to clean and all I'll shoot corrosive commie crap in any longer.
Lower? I don't clean it until it gets hairy from .22lr residue. No rust or rot on anything in there.
I oil mine with Ballistol (because it compounds with water), and cleanup involves running hot water into the upper, stripping and rinsing the BCG, and oiling as normal. Fastest thing to clean and all I'll shoot corrosive commie crap in any longer.
Lower? I don't clean it until it gets hairy from .22lr residue. No rust or rot on anything in there.
good thing was I bought a pretty cheap PSA upper in 7.62x39 which allowed to to try the caliber for a pretty cheap investment
The bad is I at first found a deal on bulk American Eagle brass ammo, and I have not been able to find a deal on bulk 7.62x39 since. My range does not allow us to shoot steel core, so most deals on 7.62x39 surplus is not an option for me. So its just expensive to shoot when I have to buy factory ammo separately in 20 rd boxs
The bad is I at first found a deal on bulk American Eagle brass ammo, and I have not been able to find a deal on bulk 7.62x39 since. My range does not allow us to shoot steel core, so most deals on 7.62x39 surplus is not an option for me. So its just expensive to shoot when I have to buy factory ammo separately in 20 rd boxs
Phat Eagle
CGN Ultra frequent flyer
- Location
- Fraser Valley, BC
I have a dedicated x39 AR I used to use for training when ammo was appreciably cheaper. It ran well once I put in an enhanced firing pin and firm trigger springs. Makes it hard to just swap on a x39 upper if all your internals are tricked out with light triggers for competing with 5.56...
I love mine and used a Canadian National Arms 16” barrel and a CNA bolt. Also
Took about 5thou of the back of the bolt so that the firing pin protrudes a little more through the bolt for those hard primers.
I like modding it this way because any AR15 pin will work in it. If you modify the firing pin and it breaks then you have to modify another one.
I also drilled the gas block out and installed a 4mm Allen screw and drilled a hole through the hand guard to adjust the screw to throttle the gas down. This combined with removing the buffer bumper and filling with molten lead and reinstalling the bumper gives you a 4.10oz buffer and greatly reduces recoil.
My 7.62 has the same recoil as my Colt HBAR as a result of this and was cheap and fun to do.
I get 2” groups with Chinese surplus and think that’s pretty damn accurate for surplus
My Czech ammo was 4” so maybe I got lucky but I shoot this rifle all the time at gongs and it’s cheap and fun
Took about 5thou of the back of the bolt so that the firing pin protrudes a little more through the bolt for those hard primers.
I like modding it this way because any AR15 pin will work in it. If you modify the firing pin and it breaks then you have to modify another one.
I also drilled the gas block out and installed a 4mm Allen screw and drilled a hole through the hand guard to adjust the screw to throttle the gas down. This combined with removing the buffer bumper and filling with molten lead and reinstalling the bumper gives you a 4.10oz buffer and greatly reduces recoil.
My 7.62 has the same recoil as my Colt HBAR as a result of this and was cheap and fun to do.
I get 2” groups with Chinese surplus and think that’s pretty damn accurate for surplus
My Czech ammo was 4” so maybe I got lucky but I shoot this rifle all the time at gongs and it’s cheap and fun
