7.62x39 AR Question

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Nexionthesub

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So new guy question here: I never even thought about building an AR in 7.62x39 until a couple days ago and thought the idea would be kick ass. Although I've already started assembling one for 5.56.

So my questions is this; is the only difference between the 5.56 and 7.62x39 the barrel, bolt, and mags? (In other words I can continue with my current lower/upper/buffer tube etc. that I have).

Thanks to anyone who can help or direct me to a source for this type of build, much appreciated :D
 
Lots of info on light primer strikes so I won't bother to chime in

As far as bolts go, where you need to be careful is most of the readily available bolts for 7.62X39 are opened up 5.56 bolts .

Won't go into details but this is why for years Alexander Arms for years made licensed 6.5 Grendel barrel makers buy his bolts ( SAE 9310 steel ...not going to get into the 9310 vs Carpenter 158 steel debate ! ) instead of resorting to 7.62X39 bolts ( like CSS did for their 6.5 )

Anyhow, some of the specialty parts makers AR performance made the 7.62X39 "superbolt" also from 9310 . This was the best choice for 7.62X39 bolts for years , even over the MGI unit . Unfortunately they are hard to find since they don't make them anymore

The best 7.62X39 bolt is the LMT Enhanced . It's a non catalog item and you need to ask for it. They should still have some left . Questars had some way back when

Having said all that, the every common but much align DPMS 7.62X39 bolt has served me well for 2500+ rounds. Only reason I use it as spare is I picked up the LMT Enhanced and has been chugging away for at least 1500 rounds
 
If you want to make your mags more reliable you should:
-reduce the height of the front of the mag by a couple mm.
-ensure the lips are wide enough to let a round out, some require filing (ASC have inconsistent lip spacing).
-file the inside of the lips to remove burrs (ASC seem to have quite a few).
-Reduce the length of the longer follower leg by approx 5mm to allow the mag to seat on a closed bolt.
 
Personally I would skip going 7.62x39 in an AR, the cartridge has too much taper to feed well from a straight magazine. You usually get away with it in 5 round mags and some of the 10 round mags seem to work but it's not an ideal combination.
I would look into 300 Blackout if you want to do something different in an AR. The cartridge is best for reloaders unless you have lots of cash for ammo but it is a great cartridge and my 9.75 inch barrel is getting close to 1 moa at 100yds with my 110gr handloads.

When it comes down to it though the 5.56 is the best round for an AR in Canada, we can't use them for anything other than punching paper or doing 3-gun and other competitive shooting events and 223 is the most reliable and flattest shooting of the 3 options. If we could hunt with them or use them for anything away from the range then some of the other options make a lot more sense.

It's up to you but to me the 7.62x39 is not a cartridge for any rifle designed to use AR mags.

There is a reason they are shaped differently.
attachment.php
 
What? The rounds do not feed on a taper, the lower mag body is tapered so the round cycle better in the magazine.

The top portion of the mags are straight and both sit level at the top. Dont they??
 
ESTRADA said:
What? The rounds do not feed on a taper, the lower mag body is tapered so the round cycle better in the magazine.

The top portion of the mags are straight and both sit level at the top. Dont they??
Click to expand...

Do you see a lot of 7.62x39 AR's in the US where they can use 30 round mags? Would the AK have a banana mag if a straight mag would work just as well?
Did Rock River Arms create the AR that takes AK mags for nothing? http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=558&
They would never have spent the money to develop that if the round worked well in the AR mag.

The 7.62x39 doesn't feed well from 30 round AR mags. Like I said, we can get away with it here being limited to 5 rounds but even some of the 10 round mags have problems.
 
cr5 said:
There is a reason they are shaped differently.
attachment.php
Click to expand...

The 30 round 7.62x39 AR mags aren't straight.

cr5 said:
Do you see a lot of 7.62x39 AR's in the US where they can use 30 round mags? Would the AK have a banana mag if a straight mag would work just as well?
Did Rock River Arms create the AR that takes AK mags for nothing? http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=558&
They would never have spent the money to develop that if the round worked well in the AR mag.

The 7.62x39 doesn't feed well from 30 round AR mags. Like I said, we can get away with it here being limited to 5 rounds but even some of the 10 round mags have problems.
Click to expand...

The 7.62x39 mags (30/5s and 10 round pistols mags) do have issues as they are sold, but with modification they can be made reliable. I've gone shooting with a few members here that can attest that mine functions 100%. Getting 7.62x39 for $0.18/rd I am still saving 6 or 7 cents off the cheapest .223. Not that those savings will ever surpass the cost of my system (Citizen Arms + Short Dot), I just enjoy variety.
 
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cr5 said:
Do you see a lot of 7.62x39 AR's in the US where they can use 30 round mags? Would the AK have a banana mag if a straight mag would work just as well?
Did Rock River Arms create the AR that takes AK mags for nothing? http://www.rockriverarms.com/index.cfm?fuseaction=category.display&category_ID=558&
They would never have spent the money to develop that if the round worked well in the AR mag.

The 7.62x39 doesn't feed well from 30 round AR mags. Like I said, we can get away with it here being limited to 5 rounds but even some of the 10 round mags have problems.
Click to expand...

Its the magazines that are the problem , the 7.62x39 AR magazines used a curved body aswell. The curved body has nothing to do with the feeding problems at the bolt. The crappy mag lip and indents on the mag make the cartridge hang up in the magazine.
 
I've heard that Ar-15s in 7.62x39 wear/break parts quicker due do more energy in the round.
If this is true, id go for the 300aac blackout over 7.62x39
 
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