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....