Custom AR in 7.62x39 setups? Pros, Cons?

[jenznat0r]

Just curious if anyone on this forum has a custom built AR chambered in 7.62 x 39. I am happy and stupid enough to say enough that my very first AR build ever is in this caliber. Definitely a pretty steep learning curve getting parts to work reliably compared to the 5.56 (or so I hear) and my set up has definitely not been trouble free. I know I am a new member, but I would be happy to extend some advice to anyone considering this type of build if they are interested in diving deep into it.

If this is in the wrong section, it can be moved.

[Aardvark]

I've been considering the PSA KS47 or CMMG Mutt due to their taking standard AK mags. If I built from scratch, the lower would have to take AK mags, but I understand standard uppers aren't wide enough. Anyway, has anyone modified an 80% lower for AK mags? Or does anyone make an 80% AK mag lower?

[jenznat0r]

I considered the PSA KS47, but I already had a stripped lower...and I wanted to shoot a fun plinking high caliber round...so I settled on BCA x39 upper. Do yourself a favor, avoid BCA at all costs. Great shell and low cost, but the bolt carrier group that came with it was garbage. Had to buy a fail zero bolt just to get it working smoothly.

[fright88]

I considered the PSA KS47, but I already had a stripped lower...and I wanted to shoot a fun plinking high caliber round...so I settled on BCA x39 upper. Do yourself a favor, avoid BCA at all costs. Great shell and low cost, but the bolt carrier group that came with it was garbage. Had to buy a fail zero bolt just to get it working smoothly.

What kind of problems were you having with the BCA BCG if you don't mind me asking? I ask because I've been thinking about picking one up in a few months just to mess around with since I heard they were working better since they upgraded the ejector.

[cstone]

Magazines will always be the problem. If you are just standardizing on a caliber, stick with what the caliber was designed for; AK or SKS. If you are just looking for similar ballistics of the 7.62x39, have you considered the 300 Blk? All the AR magazines you could ever need will take the 300 Blk, along with the 5.56/.223 with just changing uppers using the same magazines.

[Eric P]

I've been considering the PSA KS47 or CMMG Mutt due to their taking standard AK mags. If I built from scratch, the lower would have to take AK mags, but I understand standard uppers aren't wide enough. Anyway, has anyone modified an 80% lower for AK mags? Or does anyone make an 80% AK mag lower?

I just finished a ks47 sbr pistol. Need to take it out and test it.

[Great-Kazoo]

I considered the PSA KS47, but I already had a stripped lower...and I wanted to shoot a fun plinking high caliber round...so I settled on BCA x39 upper. Do yourself a favor, avoid BCA at all costs. Great shell and low cost, but the bolt carrier group that came with it was garbage. Had to buy a fail zero bolt just to get it working smoothly.


What kind of problems were you having with the BCA BCG if you don't mind me asking? I ask because I've been thinking about picking one up in a few months just to mess around with since I heard they were working better since they upgraded the ejector.

Yes what issue did you have? I have a BCA 16" Heavy upper running a Franklin BF3 trigger. Thing runs great and keeps ticking.

As for the ejector my upper is almost 2 yrs old. However they like other mfg stand behind their product.

[jenznat0r]

I actually had a local gunsmith here in Idaho modify the feed lips on all my mags to more of an “AK” style so feeding the round from the BCG would be a lot easier. With the original design, I had failure to feeds all day long. The c-products mags are by far the best on the market, and even those required some modification. The BCG on my upper was total garbage, the roll pin on it for the extractor was too long from the factory and my gunsmith had to file it down. Constant hang ups and failure to feeds with that thing. I ended up sacrificing that bolt and putting something on it called the “Kali Key” which converts your AR to a single shot, straight pull. The fail zero on it currently solved ALL of my problems. Runs like a dream now.

Slightly off-topic, but I called my Dad last night and talked to him about some of my setups. Mentioning this one he said, “you really like to build oddball, not common stuff don’t you? Why don’t you just build normal stuff that works right out of the box?”

[ray1970]

Sounds like dad is a wise man. Lol.

[jenznat0r]

Magazines will always be the problem. If you are just standardizing on a caliber, stick with what the caliber was designed for; AK or SKS. If you are just looking for similar ballistics of the 7.62x39, have you considered the 300 Blk? All the AR magazines you could ever need will take the 300 Blk, along with the 5.56/.223 with just changing uppers using the same magazines.

.300 blackout is a LOT more expensive than steel case Russian 7.62x39....

[buffalobo]

Sounds like you already spent money for Smith to fix issues that would normally not arise. The hassle of not having use of a firearm cause it has to be fixed also carries an opportunity cost.

[cstone]

.300 blackout is a LOT more expensive than steel case Russian 7.62x39....

Less expensive if you reload.

[Hoser]

.300 blackout is a LOT more expensive than steel case Russian 7.62x39....

Not if you reload.

And you dont have to worry about corrosive ammo.

[jenznat0r]

Maybe when I’m out of college and have a house, I’ll consider some reloading equipment. The ammo I currently use is non-corrosive.

[stevew]

I have a couple of 7.62x39 uppers to play with steel cased ammo. Had issues with one and was told to use the oring under the extractor to change the timing a bit and after that and finding the right mags to work I really like the extra thump it seems to have over the normal 55gr 556 rounds I shoot. They have been solid since I got them running right.

[The Extractor]

I built a franken gun out of an mgi hydra AK magwell , an 80% lower, and a youngs hd bolt with more meat around it so it doesnt break, dpms low pro slick upper milled to fit the mags and a KAK mid length barrel 18" ?
It ran a couple 10rd mags just fine.

[Great-Kazoo]

I built a franken gun out of an mgi hydra AK magwell , an 80% lower, and a youngs hd bolt with more meat around it so it doesnt break, dpms low pro slick upper milled to fit the mags and a KAK mid length barrel 18" ?
It ran a couple 10rd mags just fine.

CPD mags for the win
https://www.joeboboutfitters.com/C-Products-7-62x39-AR-15-Stainless-Steel-Magazines-p/cpd-762x39-mag.htm

[jreifsch80]

300 blackout will be the same price as 7.62x39 once all the distributors get stocked up

https://www.targetsportsusa.com/wolf-polyformance-300-blackout-ammo-145-gr-fmj-steel-case-300blkfmj1-p-110259.aspx

[The Extractor]

I wanted it to take AK mags and I guess I wanted a challenge. The x39 std AR mags are unreliable form what I read.

[jenznat0r]

I wanted it to take AK mags and I guess I wanted a challenge. The x39 std AR mags are unreliable form what I read.

Not the ones I've used from C-Products Defense. I hear the 10 round ones are even more reliable because they lack the straight down and bend design the AR is forced to use. Honestly? In the standard AR upper/lower configuration, get yourself a Black Rifle Arms or Fail Zero Nickel Boron bolt and all the reliability issues disappear. The bolt is literally the make-or-break issue in this setup, so spend the extra and get it to work work right.

Not related, but I have something called a "Kali Key" mated to my original bolt done by a gunsmith here. I rarely use it but sometimes I put it in to try it out. I use steel case ammo. Does anyone know why when I fire from a single shot with the Kali Key, the bolt refuses to retract for awhile? Is it the steel case expanding in the chamber?

[Great-Kazoo]

Not the ones I've used from C-Products Defense. I hear the 10 round ones are even more reliable because they lack the straight down and bend design the AR is forced to use. Honestly? In the standard AR upper/lower configuration, get yourself a Black Rifle Arms or Fail Zero Nickel Boron bolt and all the reliability issues disappear. The bolt is literally the make-or-break issue in this setup, so spend the extra and get it to work work right.

Not related, but I have something called a "Kali Key" mated to my original bolt done by a gunsmith here. I rarely use it but sometimes I put it in to try it out. I use steel case ammo. Does anyone know why when I fire from a single shot with the Kali Key, the bolt refuses to retract for awhile? Is it the steel case expanding in the chamber?

Cause the KK is used to make the BCG a single shot item. Not meant for semi-auto So you're experiencing a super delayed cycling . Now if you're interested in selling it, i have an interest.

Also using steel case x39 should have no effect for cycling a semi-auto Ar. I know mine has no issues. As it's all i run.

The Kali Key simply drops into any mil-spec AR style rifle and removes it from the definition of an assault weapon as defined by The Assault Weapons Control Act. It works by converting any mil-spec, gas operated (non-piston), semi-automatic rifle into a straight-pull bolt action rifle, without requiring any milling or modifications to the gas system.

[jenznat0r]

Cause the KK is used to make the BCG a single shot item. Not meant for semi-auto So you're experiencing a super delayed cycling . Now if you're interested in selling it, i have an interest.

Also using steel case x39 should have no effect for cycling a semi-auto Ar. I know mine has no issues. As it's all i run.

The Kali Key simply drops into any mil-spec AR style rifle and removes it from the definition of an assault weapon as defined by The Assault Weapons Control Act. It works by converting any mil-spec, gas operated (non-piston), semi-automatic rifle into a straight-pull bolt action rifle, without requiring any milling or modifications to the gas system.

I'll PM you.

[TrijiconJoe]

I have a KS 47 pistol from PSA. It has been an awesome gun. I have been running it suppressed and it is a bit over gassed but extreme accurate. I have a Vortex 1X4 power scope on it and can hit steel deer size targets out to 500 yards.

[BPTactical]

The thing I have to ask myself with an AR in 7.62x39 is this:


WHY?

[CS1983]

The thing I have to ask myself with an AR in 7.62x39 is this:


WHY?

Ammo cost, .30-30 levels of ballistics in a semi-auto (/s), but mainly ammo cost.

[bjordan672]

I have the KS-47 as well and swapped the Barrel for a 16" Faxon. It shoots better with steel cased ammo (0.75 - 1.4" at 100 yds) than any AK/SKS I have ever shot.

My reasons for going that route were:
1. I can hunt with it
2. Ammo is dirt cheap and plentiful ( Barring the current ammo malfunction)
3. I prefer the ergonomics of an AR
4. Easy to mount optics
5. It accepts most standard AK mags including the Drum
6. Everyone in my family is familiar with how to use an AR
7. Muzzle Treads work with standard 30 cal suppressors
8. Significantly lighter than AK/SKS