7.62x39 AR questions

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xxjumbojimboxx

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Hello High Roaders!
I always come here for answers because its a glorious database of firearms knowledge and I know I'll get some answers here. So here goes. I'm thinking about building an AR15 in 7.62x39. The thing is I know very little about ARs at this point. Ive only had one and sold it off pretty quick after the panic because I was offered a price that was too appealing to not sell my olyarms AR.

So here's the questions.

Can you use a standard ar15 lower. I think so but I just want to make sure?
Can I build the upper myself, and whats involved. (I'm handy, and I have an ar15 armorers tool)
When building the upper, I know I need m4 style feed ramps. Is this something that's able to be swapped out of an upper freely?
Id like to use a longer barrel to get more accuracy. The point of this is to get better accuracy out of a semi auto rifle in 7.62x39... does that round work well out of a longer barrel? Most of the stuff that shoots that round is relatively short.. is that for a reason?

I think that's it. If you have anything else you could add that i may need to know that would be very helpful.

** oh and please dont send a discouraging response... I know this is something i want, I know the internet has put a negative stigma on these....**
 
Well you're going to be disappointed I'm afraid. 7.62x36 does not jive well with AR-15 magazines. So my answer would be no.

In general you're probably not going to see too much of an advantage from the longer barrel. It's not going to change the rainbow trajectory of the round. Not that that's a bad thing it just requires more correction. The shorter barrels are used because they're generally all that's required to get the bullet out to its effective range.

Sorry if that's discouraging, but stigmas exist for a reason sometimes. There are other platforms much better suited to the x39 than the AR.
 
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Thanks comrad

Its my understand that the hi cap mags faulter, where the 10's and 20's rarely have issues.

Its also my understanding that modifications can be done, and there are better mags to be had for this platform that aren't faulty. Though even those can be hit or miss...

Either way I'm still sold on it. Anyone else?
 
I am not a LegoGunner, but just to get things started...

Can you use a standard ar15 lower. I think so but I just want to make sure?

Yes. The limitation is getting workable magazines. Somebody makes an AR lower that takes AK magazines, but it is expensive.

Can I build the upper myself, and whats involved. (I'm handy, and I have an ar15 armorers tool)

Beats me. There are a lot of amateur ARs out there, but I bet there are some ruined parts on shelves, too.

When building the upper, I know I need m4 style feed ramps. Is this something that's able to be swapped out of an upper freely?

M4 feed ramps are machined into the barrel extension and upper. They are not something to be "swapped out."

Id like to use a longer barrel to get more accuracy. The point of this is to get better accuracy out of a semi auto rifle in 7.62x39... does that round work well out of a longer barrel? Most of the stuff that shoots that round is relatively short.. is that for a reason?

A longer barrel serves accuracy only when used to give longer iron sight radius. A short stiff barrel will do as well or better with a scope, or if you are using the regular front sight tower on the gas block.
The real key to better accuracy will be better ammo.
 
Thanks Jim.

" Somebody makes an AR lower that takes AK magazines, but it is expensive."

Expensive, Hm, I have like a hundred AK mags... It may totally be worth it to go with that.

"M4 feed ramps are machined into the barrel extension and upper. They are not something to be "swapped out."

So when I purchase these parts i need to make sure they have m4 ramps already built in. Got it, Thanks.


Now I'm just looking to see if anyone can give me the skinny, or a link to the skinny, on building your own upper from scratch.
 
Youtube has plenty of upper build videos. You'll need a good vice, action blocks for the receiver and a torque wrench. It isn't hard, I assembled a .22 AR upper a few months ago for the 1st time.

Another problem with the 7.62x39 is the bolt. The AR bolt lugs are already a weak point in the design. The much larger bolt face for the x39 makes them even weaker so you may not get good life out of the bolt. If you handload, the 300BLK will be much better. Easy to find .30 cal projectiles, uses standard AR bolt and magazines. None of the downsides to 7.62x39. Big downside is ammo price and availability.

If you don't handload, the x39 is worth the downsides I'm sure since the cheap ammo makes up for them. I'd stick with a 16" barrel, no need to go longer, it won't be more accurate and you won't gain that much velocity.
 
Well you're going to be disappointed I'm afraid. 7.62x36 does not jive well with AR-15 magazines. So my answer would be no.
Click to expand...

Yes it doesn't work in 5.56 magazine too much case taper, you need purpose built 7.62x39 AR mags. These can have spotty quality, but most problems are curred with an anti-tilt 7.62x39 specific follower and a spring from a real AK-47 magazine.

RAA has an AR, in the works, that uses standard AK-47 magazines but it uses a proprietary upper and lower, and so far building your own is not possible. Not sure the guns are actually for sale yet.


I've a pair of 7.62x39 ARs, one a 16" carbine, the other an 11" SBR. Took me a while to get a set of magazines that work but they are now my favorite ARs to shoot. Any ignition problems with the cheap steel cased ammo are solved with the Model 1 Sales "enhanced" 7.62x39 firing pin. If your bolt breaks an MGI enhanced 7.62x39 bolt is your solution.

If your building skills are up to snuff I doubt you will be disappointed.
 
Yes a 7.62x39 uses the same lower. C-Products makes 25 round magazines for the AR and all 8 of mine functioned well. I used an ESS Solutions 16" barrel, A2 upper receiver, A2 site base that came with the barrel, handguard, barrel nut and a .308 flash hider as the barrel is threaded to fit that. I actually enjoy shooting it and haven't had any issues with steel cased Wolf, Brown bear or Barnaul ammo out of it either.
 
I built one a couple years ago with a Model 1 Sales parts kit and I use the C-Products mags as well ... I ordered mine with a flat top but I could never get a zero with a detachable carry handle, I even ordered a taller front sight post from Colt and still couldn't get there so I put a fixed handle on and problem solved ... I also had to take a few thousands off the back of the bolt to allow the firing pin a better primer strike and have had zero problems with it since and it eats all types of ammo without so much as a hiccup in the last 1200 rounds or so.

Targets were shot at 100yds ... with my nearly 60 year-old eyes in bi-vocals I was surprised I could see the targets and the sights, kinda why I wanted a flat top in the first place but after getting it done I wanted the irons.

PC020011.jpg
 
Can you use a standard ar15 lower. I think so but I just want to make sure?

Yeo

Can I build the upper myself, and whats involved. (I'm handy, and I have an ar15 armorers tool)
Same as any AR upper build, BUT finding BCGs for this is now much much more challenging now that manufactuers are dropping 7.62x39 bolt and barrel manufacture.

When building the upper, I know I need m4 style feed ramps. Is this something that's able to be swapped out of an upper freely?
No

Id like to use a longer barrel to get more accuracy. The point of this is to get better accuracy out of a semi auto rifle in 7.62x39... does that round work well out of a longer barrel? Most of the stuff that shoots that round is relatively short.. is that for a reason?
Longer barrels do not equate to better accuracy. Barrels tuned to the specific round (or the other way round) equate to better accuracy. The 7.62x39 is an intermediate cartridge and shouldn't improve with a barrel longer than 20", but then the improvement won't be significant and a 16 or even shorter barrel of excellent quality will provide better performance than a longer lower quality barrel/crown.

We have an original Colt NM 7.62x39 that my wife can put hand sized groups at 300yrds all day long with and a 11.5" AR pistol that plays well. Finding the right magazines is key to function.
 
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