AR Pistol in 7.62x39mm

I've been wanting an AR pistol for awhile now, and 7.62x39 is something I've been meaning to add to my collection. I Was going to just go with a 5.56 pistol, but 7.62x39 performs very well out of a short barrel. Well enough that it could be more than just a range toy.

So, after some looking I have three options to choose from. I'd appreciate some input. I'd like to keep this build as cheap as possible, but I won't sacrifice quality to save a few bucks (within reason).

I have a stripped lower and an assembled upper to work with.

OPTION 1. PSA AR-47 - ~$600

It's just a regular AR-15 chambered in 7.62x39. The only upper they currently have is not what I'd want the end result to be. It has your typical generic cheap AR drop in handguard. I'd want to upgrade it to a free float rail and remove that sight. From what I've read, C-Products Defense 7.62x39 mags are reliable. They aren't what I'd call cheap, but they're not expensive either. I could live with them.

OPTION 2. PSA KS-47 ~$700

It's an unholy mix of an AR and an AK, but it's kinda cool for that reason. It uses some proprietary parts such as the lower receiver and I think the BCG. It's claim to fame is that it can use standard AK mags. It's close enough to what I want that I'd be happy.

https://palmettostatearmory.com/psa...ght-m-lok-moe-ept-sba3-pistol-5165450182.html

OPTION 3 Homebrew ~$760

I say eff it and build my own upper using the assembled upper I already have.

Faxon 10.5" barrel - $159.00
PSA SBA3 lower build kit - $160
Faxon MuzzLok flash hider - $70
Magpul MOE K2 grip - $17
Seekings LP adjustable gas block - $56
Aero Precision gas tube - $16
Faxon 9" MLOK handguard - $121

EDIT: Forgot the BCG and CH

Strike Industries Arch CH - $32
Faxon BCG - $130

I would get exactly what I want this way, other than being able to use AK mags. I'm leaning towards this option. That, and I finally get to do something with that assembled upper I've had sitting around since the last election.

Option 3

Home grown alright with me
Home grown is the way it should be

Do you guys have any recommendations on a BCG? I know the 7.62x39 has a nasty habit of breaking bolts (I will be shooting mostly 150gr+ cast bullets, so that should be less of an issue with me), so I want one that's made to last. I assume Faxon would be GTG, but it's a little pricey, even when it's on sale. KAK had one that was about $50 cheaper, but I don't have much experience with them. Most sources online recommended Toolcraft, but I don't think they make them anymore.

Edit: Found a Toolcraft for sale for $100.

If you buy the PSA KS-47 upper and lower separately it will save you about $100 or a little more. I'm leaning towards that myself since I have a bunch of AK mags.

KS-47 is pretty compelling to me. If I opt for an AK style AR, that'd probably be it.

If you choose to go that route, C-Products Defense 7.62x39 mags have worked flawlessly.

Looking at the KS-47, I like it a lot, but I have some concerns. The main one being the bolt. I believe the carrier is just your run of the mill AR carrier, but the bolt is specifically designed to work with AK mags. Given the X39s tenancy to break bolts, that worried me. You cannot buy those bolts alone (you can buy the full BCG though), and what happens in 5-10 years when PSA drops the KS-47? You might be able to find a shop to mill a standard bolt to work, but that's a lot more trouble than I'd want.

The other issue, and this is me just being picky, is that PSA has said that their bore size is 0.3125". Not a big deal to those who shoot crappy steel case ammo, but more of a big deal for a reloader. .312-.313 bullets are out there, but they cost more and you're pretty much stuck with heavier bullets (150gr). Most 7.62x39 bullets are 0.310". As a reloader, 0.308" is probably the best due to the bullet selection and the price. I believe that Faxon had that same opinion when they made their barrels.

I could build a KS-47 for under $600, and the magazines would be about half the price if not less. I could also get one with a 8.5" barrel. The other options are limited to 10.5". That's a tough choice.

The build would end up being a bit more than I wanted to spend, but it would be a really sweet gun. I keep going back and forth on the parts, trying to balance price with function and quality. Right now, it would be between $700-$800 depending on what parts I decide to go with.

Well, after some thought, I think I may go with a Bear Creek Arsenal barrel. It's about 1/3 the price of the Faxon, and despite all of the bad you hear about BCA online, those who actually bought these barrels seem overly happy with them. I saw some pretty nice sub MOA groups with them. That's enough for me to take a $50 risk.

I have no idea what the bore size on these are. BCA claims 0.312, those who have tested claim 0.310-0.311, and I have seen sub MOA groups with 0.308 bullets.

I built one with mostly parts from kak industries, 8" barrel, extremely accurate. I broke the extractor arm in my bolt. Kak replaced it, I bought a spare and an upgraded bolt from another manufacturer. I'll post once I remember the name.

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https://www.blackriflearms.com/762x39-Melonite-QPQ-Bolt-Assembly-_p_239.html

Here it is, bought this thing, been flawless since. Worth the price, breaking that extractor arm sucks. I keep my rebuilt kak bolt and a spare extractor arm in my grip.

Definitely build your own, you get exactly what you need.

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Maverick44 said:

Well, after some thought, I think I may go with a Bear Creek Arsenal barrel. It's about 1/3 the price of the Faxon, and despite all of the bad you hear about BCA online, those who actually bought these barrels seem overly happy with them. I saw some pretty nice sub MOA groups with them. That's enough for me to take a $50 risk.

I have no idea what the bore size on these are. BCA claims 0.312, those who have tested claim 0.310-0.311, and I have seen sub MOA groups with 0.308 bullets.

Click to expand...

I had a BCA upper with an out of spec gas port. Sent it back to them and never heard from them again. Multiple emails and phone calls and nothing. Had to dispute the charge on my card in order to get my money back. Never again for me, but good luck if that is route you choose.

Maverick44 said:

Well, after some thought, I think I may go with a Bear Creek Arsenal barrel. It's about 1/3 the price of the Faxon, and despite all of the bad you hear about BCA online, those who actually bought these barrels seem overly happy with them. I saw some pretty nice sub MOA groups with them. That's enough for me to take a $50 risk.

I have no idea what the bore size on these are. BCA claims 0.312, those who have tested claim 0.310-0.311, and I have seen sub MOA groups with 0.308 bullets.

Click to expand...

A friend had a BCA barrel in 5.56 on a cheap build. It had a very tight chamber. Have seen a few BCA's with non-concentric threads

Spend the money on a faxon.

Also, BCA at one point got raided by ICE. There are better companies out there

https://abc11.com/5122017

After some thought, I decided to stick with the Faxon barrel. I think I finally have the build where I want it. As soon as I get paid, I'll order the stuff and post the specs.

I think for the price, it's going to be a very nice little set up.

I built a 16" 7.62x39 with a stainless Bear Creek barrel, the chamber was incorrect. they sent me a new one, not issues since then.

I made my final decisions, and I ordered everything. Hopefully I'll have a working gun by this time next week.

Here's the parts list.

LOWER

Spikes Tactical Spartan stripped lower
Palmetto State Armory lower build kit
- SB Tactical SBA4 pistol brace
- PSA lower parts kit with enhanced polished trigger
- Magpul MOE grip and trigger guard
- PSA Carbine buffer tube, spring, and buffer
H3 buffer (was not branded, but I believe it's a Bravo Company buffer)
C-Products 30rd 7.62x39 magazine

UPPER

Spikes Tactical assembled upper (I think)
Faxon 10.5" 7.62x39 Gunner barrel
KAK Micro Slim Line Flash Can
Seekins Precision adjustable gas block
Spikes Tactical carbine melonite gas tube
Midwest Industries SLH M-Lok 10.5" handguard
Toolcraft 7.62x39 BCG
Aero Precision charging handle

I'm going to take the Vortex Strikefire II RDS off of my 5.56 AR and stick it on this one. The 5.56 is probably going to get a Primary Arms SLx 1-6x24mm SFP scope at some point. Until then, It'll be kicking around with irons.

Waiting for the build pics, the final pics, and the range report! Hurry up!

Well, everything shipped and should be here before the end of next week. I went ahead and bought a go gauge to test the headspace on it. I'm too much of a cheap bastard to buy a no go and field gauge too, but there's an easy way around not having those as long as you have the go gauge. I'll update the thread with pics of the build and a range report once I get all put together.

I got everything for the upper yesterday, so I went ahead and got that put together.

Here's my setup. An old troque wrench, some cheap action vice blocks from AR Stoner, and one of those work benches/saw horses that can be used as a clamp. It worked OK. It would have been a little better if I had used an actual bench vise, but I don't have one. The blocks had a tendency to want to twist out of the work bench a little when you torqued down the barrel nut. They never actually came loose though.





I chose to use Super Tech Moly Lithium Extreme pressure grease on the receiver extension/barrel nut. From what I understand, it's graphite free, and I already had half a tube lying around. There's a lot of debate over what works and what doesn't. The purists out there insist on Aeroshell 33 ms. Others say anything that doesn't have graphite in it is good to go. Some say the issues with graphite are exaggerated or even non existent. I don't know, after about 30 minutes of reading forum posts arguing over the issue, I was done with it. What I used is Moly, and is graphite free. That's good enough for me.

The barrel nut instructions specified 40 Ft-lbs, so I cranked it down to that and broke it back loose 3 times to make sure the barrel was fully seated (I believe it also seasons the threads).



The nice thing about this barrel nut is that it doesn't have to be timed to work with the handguard or the gas tube.

The gas block and tube were a breeze. Using a pencil, I marked the outside limits of the gas holes on both the barrel and the block, and then just lined them up. The hole on the block is slightly larger than the hole in the barrel, so you don't have to be absolutely perfect. There is some play. I used blue Loctite under the gas block, and on the screws. I don't do mag dumps, so it should hold. The barrel does not have divots, the gas block is held by the screws. They are in there tight enough that they probably marked the barrel. Going in later and drilling a couple of divots wouldn't be much trouble. I'm not going to do that until I know the barrel is good though.



Next was the flash can. I like the look this thing has with a full length handguard. It just screws right on. You don't need a crush washer or anything unless you want to time it a certain way. The cut outs on the end did not end up being timed to where they were perfectly vertical or horizontal. I'm not sure if that bothers me enough to get a crush washer to fix it. You don't really notice it that much.



Finally, the handguard. This thing is like air. It's stupid light, and beautifully machined. It's a tight fit on that flash can too. They don't touch, but there's very little room between them. It's a friction fit handguard, but seems to be a very well designed one. It locks onto the barrel nut and around the receiver pretty tight. That, along with the textured surface on the barrel nut, and how much it clamps down on that but should keep it from walking loose.

I'll have to take it back off when I adjust the gas block, but that's pretty easy to do.

It's so tiny.



And finally, the sight. I'll put some Magpul MBUS's on it too eventually. I have a magnifier for that RDS, so I'm going to use to to help test the accuracy of some loads I made up for the gun. Once I'm happy with that, I'll probably move the RDS farther back on the receiver.

Oh, and this mag is kinda weird. I'm not used to that much curve. I stuck it in one of my other ARs, and it might take a little getting used to. It seems very well made though.



The lower parts showed up today. I'll probably put that together tonight.

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I got the stuff for the lower in, so I got that finished up tonight. I think just about everyone here has either put an AR lower together, or has at least seen it done before, so I'm not going to bore you with that. The lower is just your run of the mill lower. The only thing special is the buffer. I went with an H3. From what I understand, this will help keep the bolt locked longer, and allows the pressure in the barrel to drop more. It's gentler on the bolt if that pressure is kept low. Broken bolts are a common problem with 7.62x39 ARs, so this, along with the adjustable gas block should hopefully alleviate that problem. If I need to go heavier, I can get a extra strong buffer spring. If I need to go lighter, I can swap some of the tungsten weights in the buffer for steel weights.

The black one is a standard PSA carbine buffer, and the Gold one is an H3 (three tungsten weights).



Once I got the lower put together, I tested the headspace.

The ejector needs to be removed from the bolt to test headspace properly, Which was kind of a PITA to do (taking it out is the easy part, putting it back is not so easy). I basically stuck a empty case in a vise, used it to push the ejector in to reduce the pressure on a pin, and did a balancing act where I held pressure on the case, held a punch in that same hand, and used a small hammer to careful drive the pin in/out.

With my headspace gauge, removing the extractor was optional. It made the process easier, so I just removed it.



The gauges are not that cheap (about $30+ each), so I made due with just the go gauge. This tests the minimum headspace. A trick you can use is to use masking tape on the back of the gauge to increase it's length. The tape I used was about 0.04" thick. From what I understand A no go gauge (max headspace) is between 0.03" - 0.06" longer than a go gauge for 7.62x39. A field gauge is about 0.10" longer than a go gauge. If a gun fails a field gauge test, it is not safe to shoot at all.



With the go gauge, the bolt closed without any resistance.



With one layer of tape (no go length), the bolt barely closed, and did not close easily. It had to be forced close. I believe it is relatively normal for ARs to do this on a no go gauge.

Had the tape been just a tiny bit thicker (0.01" - 0.02"), I doubt it would have closed.

This is where it met a lot of resistance



With 2 layers of tape (not quite field gauge), the bolt would not close period. Not even close. The gun is safe to shoot and is within spec.

A range report will hopefully be coming soon.



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