Educate Me on 7.62x39 Uppers

[Speedo66]

I know you can knock out a couple of pins and change to another upper, but what magazines work in a 7.62x39 upper? Does it take dedicated magazines, AK mags, or can you load that ammo into AR mags?

Is their reliability more or less the same as a regular AR?

Remember, there are no stupid questions, only stupid people asking questions. At least that's what our drill sgt. used to say. lol

 

[Walkalong]

You need 7.62X39 AR mags. In my short experience with one the ten rounders work great, with the 20 and 30 rounders being iffy. Some say they have great luck with the 20 & 30 rounders, but not me, although I haven't tried a great many of them.

These are the ones I tried.

http://www.shop.northriverllc.com/762-x-39-AR-Magazines_c19.htm

I bought two of the 20 rounders, one of the 30 Rd Gen III and a ten rounder.

 

[boom boom]

Make sure to get a good bolt. The Russian 7.62 has a bigger case head. In an Ar 15 rifle, that means the bolt head recess must be enlarged which removes a lot of steel which can result in broken lugs. There have been differing ways to make a fix.

 

[1stmarine]

Some mags work better than others but nothing it cannot be fixed.
Also like others suggested spend a bit more in a beefed up bolt. It will pay off.
Consider there are dedicated lowers for AK magazines but I am not sure I like AK magazines unless you already have them.
I guess it depends if this if for critical duty or just for the range and hunting.

 

[ColoradoMinuteMan]

I have no first hand experience with a 7.62 AR, but based on the anecdotal stories I've heard and read I'd at least look into dedicated lowers for a 7.62x39 AR as 1stmarine mentioned.The standard AR magazine well is straight and long. 7.62x39, being a tapered cartridge feeds more reliably from a magazine that is curved all the way from the feed lips to the floor plate. There's also the bolt issue which is unavoidable. They may have that solved in present day generations but there is no avoiding the fact that there is just less meat on a 7.62x39 bolt due to the diameter of the case head. You'll have to determine if the risk of breakage is valid enough to keep you away from using one.

 

[WhoMe?]

It really depends on what you are looking to get out of an AR in 7.62x39 since the AR obviously wasn't designed around this cartridge. If you want to just pop some pins out and switch you will have some compromises in feeding reliability and bolt but I've never actually had issues with mine. I went cheap because mine is just for fun and I wanted to maintain compatibility with other AR stuff so I went with just an upper and some mags. If you are looking for a dedicated 7.62x39 AR you may want to consider some more specific parts (with less interchangeability). When I started looking into a dedicated 7.62x39 AR the end product was expensive and really wasn't very "AR-like" to me so it just didn't make sense for me. I figured I was better off at that point getting something truly designed for that cartridge or just going with the upper and mags for fun.

 

[wally]

Some say they have great luck with the 20 & 30 rounders, but not me, although I haven't tried a great many of them.

I've been able to fix most of the 30 rounders by swapping in the spring from a real comblock AK magazine. Curiously the spring from the 7.62 AR mag worked fine in the AK magazine -- at least for normal range usage shooting steel plates. I've also found the Wolfe "extra power" AK replacement magazine springs work as well.

But I've found with all the 7.62 AR magazines -- 10,20,30 rounds -- some JHP rounds with a flat front and shorter OAL than the normal XM193 can slip forward under recoil, the flat front presses against the magazine body and the rounds taper combined with the strong magazine spring wedges it, causing a feed failure. I suspect exposed lead soft point rounds could have the same issue.

As to parts breakage, stuff breaks, if yours does fix it and keep shooting! MGI makes an "enhanced" 7.62x39 AR Bolt and Model 1 Sales sells an "enhanced" firing pin if your lower has trouble setting off the hard primers in surplus 7.62x39 ammo.

For hunting where you likely have a 5 round capacity restriction I've never had a failure of any kind with any ammo or any magazine when five or fewer rounds remain.

 

[desidog]

As has been noted, the weak point is the bolt's lack of meat around the case head; because the .223 case is a smaller diameter than the 7.62x39 case.

I have had zero issues with the C-Products 30 round mags.

 

[1stmarine]

It is my experience the bolt issues have been fixed by using stronger alloys and a wider radius at the base of the lugs.
Young, LWRC, ARP are good examples. They will not break and they have been running w/o hiccups with higher pressure cartridges.
I have made substantial efforts to break one up to 65k psi and have failed after ruining some cases.
Well worth the money and consumers should demand that quality and have chambers matched to the bolts with quality parts.
The problem comes with sweet deals and cheapo parts kits that try to shave dollars on every item, including critical ones.
Even some reputable makers have been using subpar parts that look great on the outside with nice skulls and tacticool logos
but the materials and manufacturing under the hood are not up to the task.
This is specially hard to detect because many rifle "makers" do not make anything. The buy from OEM providers that rebrand the parts
and have no processes no infrastructure to test the quality. remember the huge recall on Stoner bolts form midway when
they started to break left and right? Midway who have amazing customer service recalled and replaced everything right away but
didn't invest one minute in testing to make sure the bolts were properly heat treated otherwise they would not have sold
any. Actually some stoner parts are pretty decent quality but this is not the point.
the point is that in order to get something good make sure to put some time understanding what is good and be willing
to pay a bit extra for quality stuff. So before you buy form the latest model1, PSA, rguns, etc.. bottom barrel deal think a bit
if spending a bit more makes a huge difference on a budget when, at the end of the day, you factor the cost of ammunition.

 

[BigBore45]

i had one a few years ago that i shot around 1000 rounds through. no problems on my end. got quality mags and i think all the newer bolts are good. it was pretty accurate at 100 yards with cheap wolf/tula hp ammo would get around 1-1.5" groups consistently. my friend really wanted it and i decided to let it go and consolidate some calibers. He still has it and it rides in the pickup with him as a coyote/deer truck gun when he checks cattle and stuff. he never complains and its still running.

 

[salt&battery]

If you have the extra money the mutant from CMMG. the lower is made to use steel AK mags the best mag design ever and has a bigger bolt not a hogged out 5.56 bolt which is barely big enough for the 5,56

 

[kBob]

Back when the first of the 7.62x39 uppers were coming out there were no 7.62x39 AR magazines.

As folks have noticed the M43 cartridge has a bit of taper to it.

I saw people load and fire as many as 12 rounds of M43 into standard 20 round AR mags......but for dependable operation they loaded nine rounds.

30 rounders held only a few more rounds for reliable feeding though sometimes folks got 18 to work, but again IIRC 14 was about it for dependability.

If you will look at some of the dedicated 7.62x39 guns you will see the mag well modified as that straight section is not good for M43 feeding.

-kBob

 

[Casefull]

I have several and they run fine with the correct mags. You do not need the dedicated '39 receivers. I run 25 rounds in the 30 round mags without any feed problems. They make a fine alternative to 5.56 when you need to hit harder and make a bigger hole. I have one with a 10 inch barrel that shoots 1 moa with a scope. The russian round does real well in short barrels...tula ammo clocks a little over 2200fps out of 10 barrel. Lots of misinformation on the internet. Unfortunately it comes here on the forum too.

 

[Walkalong]

with the correct mags.

Which ones are those, specifically. A link to ones that have worked 99/100% for you would be nice.

 

[rbernie]

A while back, I observed found that ammo brand had a consistent impact on feeding reliability, with brass cased being most likely to feed well and laquered cases being meh and polymer coated cases being the worst. The shape of the round stack in the AR magazine profile isn't really ideal for the 7.62x39 round diameter (AK magazines are wider by a good bit, for a reason), and cases that have any sort of 'grab' to them simply make it worse as the round stack height increases. Stiff magazine springs and anti-friction spray coatings in the magazine body certainly help overcome this limitation, as does lower capacity magazines in general.

 

[DMK]

Regarding feeding reliably, this is an interesting article. I haven't tried this on mine but it looks like a simple solution that makes sense.

http://www.alloutdoor.com/2014/11/25/making-ar-15-7-62x39-work-reliably/

 

[<*(((><]

Magazines: ASC and C-Products mags work the best, I personally like the C-Products better, as they have clearanced the magazine right in front of the point of the bullets about an 1/8" to allow the shorter cartridges to not hang up on the front section of the magazine. If you look at the picture below people have started to dremel their own magazines in front of the bullet sitting in the magazine to prevent the cartridge lip from catching. C-Products magazines (at least the ones I've bought) have clearanced them.

Bolt: Buy a high quality bolt that is made of a good alloy like the AR Performance Bolts, Lewis Machine and Tool, and I believe AIM Surplus carries a decent one as well.
Feed Ramps: Some barrel manufacturers are widening the feed ramps in the middle section between the two ramps for better feeding, If the cartridges are nose diving and failing to load people in the past have taken a dremel and widened those themselves and polishing them afterwards (Added for clarification :I never had an issue where I had to do this). The picture below is more of an extreme example, I don't think one needs to take that much material out of the feed ramps if having problems but it gives you an idea.

Firing Pin: Get an enhanced firing pin for the 7.62x39, it has a longer protrusion that will reliably ignite the harder russian primers.
Hammer Spring: Milspec or heavier hammer springs for reliable ignition. Some people have had no problems even with lighter hammer springs with the enhanced firing pin, but if ignition problems occur on russian ammo, look at the firing pin and hammer spring.
Buffer: It seems that most are running carbine H2 buffers.
Gas System: Most are running carbine or midlength gas, there have been reported problems of not getting enough velocity on the carrier from going to a rifle length.

I enjoy mine, cheap to shoot and a good hunter for deer sized game and smaller.

 

[wally]

Regarding feeding reliably, this is an interesting article. I haven't tried this on mine but it looks like a simple solution that makes sense.

http://www.alloutdoor.com/2014/11/25/making-ar-15-7-62x39-work-reliably/

The article says:

If you have feeding issues, Dremel out the middle of the M4 feed ramp, and it’s likely any feeding issues you are having will disappear.

I've never needed to do any such things and I have 7.62x39 AR in 16", 11", & 7.5". I shoot only polymer and some lacquer coated steel cased ammo.

Before breaking out the Dremel, I'd strongly suggest replacing your magazine springs with the spring from a real comblock AK mag, or maybe a Wolfe extra power AK magazine spring like I mentioned in post #7.

The problems I mentioned with some JHP rounds I have no solution short of significantly downloading the magazine to reduce the "wedging" force should one of the top few rounds move forward under recoil and push the tip against the front of the magazine body preventing it from moving up to feed.

 

[<*(((><]

Like Wally was speaking to, I would save the feed ramp adjustments for last, I should have pointed that out first. I was more pointing out what some have done to resolve some early issues with the 7.62x39. I'm not so sure that many are having to do those now a days with builds, as magazines have gotten better and I think that some barrel manufacturers are doing their own adjustments. My Yankee Hill Machine barrel hasn't needed any work on the feed ramps it came with, and they seem to me to be wider than typical M4 feedramps.

Salt&Battery: While I'm sure the CMMG Mutant is a great rifle. I wanted an upper that can drop into my lower. You can't do that with a mutant. But the mutant has it's own benefits, being a larger bolt face and can take AK mags. For me the choice was simple as I wanted another upper to put in a pelican case with my others that can be swapped around and not another whole rifle.

My first post probably scared some people in thinking that it's a nightmare undertaking. My experience has not been that, my experience has been, buy the right bolt, firing pin, and magazines and it has ran fine for me. I didn't have to do any of the things that I mentioned above that people have done in the past. I should have said that in my first post, I was more pointing out what has been done over the years before manufacturers sorted things out.

 

[Casefull]

Which ones are those, specifically. A link to ones that have worked 99/100% for you would be nice.

AR Stoner mags from Midway USA.

BTW I shoot tula, wolf, various brass ammo, and lots of bullet weights with my handholds and have never had a jam or a problem with 4 different rifles. I understand some have teething difficulties with these. I have Model 1 sales rifles and PSA uppers and all are accurate great setups. So from my perspective I do not get all the problems that others have had. Of course I seldom have problems with my semi auto pistols either. lol

 

[AndyP]

I would add that the Geiselle 2-stage triggers use full power springs and will ignite all of the hard primers without giving you a hard trigger, as would putting a stronger spring in a stock one would do.
I love my 7.62x39 AR's. Just as reliable or more so than my Bushmaster .556, and print 1.5" groups with Brown Bear at 100 yards. Shoots pretty flat out to 250, and I still have pretty decent groups out to 400 yards, which is as far as Ive shot it.

 

[Walkalong]

I have had no problem with feeding or setting off ammo, just hangups in mags where the rounds stick and the spring can't push them up. I'll just use 10 rounders if I have to.

 

[Speedo66]

More questions. OK, I now know that there are dedicated mags, although some say the original mags will work. I thought a complete new upper was necessary, but is it just the bolt and barrel that need to be changed? Assume I know nothing about this, which would be close to the truth.

Thanks to all for sharing your knowledge.

 

[Casefull]

The only way the 5.56 mags work is with a few rounds in them, i.e. less than 10 in a 30 rounder and maybe 5 in a 10 round mag. As has been previously stated the wide base of the '39, compared to more even width 5.56 case, necessitates a more aggressive curve in the magazine and a heavier spring. Lift a loaded 30 round ak mag and compare that to loaded 5.56 mag...a huge difference.

 

[maxxhavoc]

All I did was built a standard lower and slap a PSA 16" 7.62x39 Upper on it. I use cheap ASC mags, Wolf ammo works great. I get feeding issues after 50 rounds of Tulammo, but that happens sometimes in the SKS as well. A quick chamber mop and it is good to go again.