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Thread: Input requested: AR-15's in 7.62x39

  1. #1

    Input requested: AR-15's in 7.62x39


    I hope this note finds you all well!!

    I am unsure if this has been covered here before (I did do a search and had a good look before I posted but I have been known to make an omission every now and then)

    However as you all are a cadre of experienced, knowledgeable and dedicated shooters (that's why I post here!!) I would like to get some feed back.

    A good friend and I are once again considering doing a build in 7.62x39. Further one built in such a fashion to take advantage of the inexpensive and plentiful corrosive surplus ammo.

    I was wondering what your experiences have been, and what pitfalls might have been encountered.

    I have already built an upper, and I let some one talk me out of it.

    It was a 16" colt barrel (post ban so it was not threaded at the muzzle) with appropriate bolt.

    I sourced the parts to complete the BCG and built an upper.

    To leave as much metal at the muzzle as possible, I had it threaded by a local smith 9/16 x 24 (The same thread used for 6.5 Grendel)

    At the same time I had two custom muzzle treatments and a thread protector made up an it looked as follows:

    This build coincided with Canada Ammo importing non-corrosive 7.62x39 Surplus (steel jacket lead core projectiles) that seemed to come from Saudi Forces.

    It was a copper washed sort of ammo that was actually really reliable, relatively accurate and clean shooting.

    Further, Robinson Arms 10 round LAR mags with the gen 2 followers that fed both 7.62x39 & 6.8 SPC were relatively new on the scene as well.

    Three friends and I took it, one of my course lowers, most of a spam can of ammo, and around 8 - 10 RA LAR mags to the indoor range.

    We spent the next 2-3 hours shooting it, and putting as many rounds through it as we could.

    350-400 rounds later, it was smoking hot (burring the oil off) and we could not make that upper fail, and all the 10 round mags functioned flawlessly.

    I was very impressed, and the only reason I let it go was the indoor range to which I was a member prohibited the use of steel core AND steel jacketed ammo.

    Well what goes around comes around, and such a build is back up for consideration, with real concerns for reliability.

    Mine worked well, but I have seen other with issues. At TacticalTeachers Service rifle CQB course there was a gent using an NEA 7.62x39 and he had a few issues that I helped him work through.

    I thank you for your time and look forward to all your constructive responses.

    warmest regards

    Last edited by AbHobbyist; 01-05-2018 at 08:59 PM.

  2. #2
    I haven't built one of these. However every once in a while I go back to looking at what's involved in a build for this calibre. The below is what I learned back when I was thinking of going this route with an AR:

    The concerns I would have with a 7.62x39 AR are:

    1) Corrosive ammo and the gas tube. Now that being said, I always flush out my CZ858 with very hot water and windex. It dries in minutes and then I spray it down with G96. If you do this within a few hours after shooting then there is no rust. A piston system upper might be of some advantage here if you plan on using corrosive. Personally I like using corrosive in a 7.62x39 as they tend to be cheaper.

    2) Bolts have been known to sheer lugs and steel case is usually avoided with AR rifles as it's hard on the extractor. The bolt face being enlarged is believed to weaken it so lugs can sheer off. But.. this can even happen with 5.56mm as well. You can find examples around the net.

    3) Magazines. The 7.62x39 likes a curved magazine to feed reliably. Hence the AK mags/CZ 858 mags etc. A straight line for this round can cause issues.

    4) The round is a 2-300 yard round. 5.56mm especially with heavier 77 grain is good for about twice that. It's easier to get match grade bullets as well if you decided to shoot further out.

    The KAC SR-47 and Rock River Arms LAR-47 both use AK mags for their 7.62x39 rifles. Also the .300 BLK was designed to pretty much be an AR friendly 7.62x39 that also works very well suppressed.

    Now that the above is out of the way.....

    Most of those issues can be mitigated. First clean quickly with very hot water down the barrel, spray with windex, then hot water again. I use a laundry room sink that gives enough depth for this. So the corrosive ammo issue is gone. This allows what was once very cheap surplus ammo. That ammo was $160 for 1200 but has doubled since I bought a crate. It's climbing in price. But you can still find bulk surplus around and it's cheaper than 223/5.56 by enough to notice. Also there is a lot of no corrosive ammo out there these days. So concern 1 is now taken care of.

    Concern 2. There are enhanced bolts that are designed for the 7.62x39. Worth looking at those.

    Concern 3: Magazines. We can only load 5 or maybe 10 rounds per mag. So the curved bannana mag requirement for regular capacity mags isn't unfortunately an issue here in Canada.

    Concern 4: Most people won't be shooting further since the AR is restricted and they are relegated to a range only firearm. Most ranges are max 300 metres. So again not really an issue in most case.

    It's an interesting project. I think it's a good one. Especially here in Canada due to the AR being restricted and our mag limitations. I have however noticed surplus ammo double in price. For ammo you're also competing against the SKS, CZ858, T81 etc. Probably not the MX10 though...
    Last edited by Full Metal Jacket; 01-06-2018 at 05:18 AM.

  3. #3
    Join Date
    Apr 2015
    Surrey, BC
    I bought a Dlask upper a few years back, it had a unmark SS 14.5" barrel, I suspect they were made from Lothar blanks, because Dlask had some 22 and 30 Lothar barrel blanks in the inventory around that time. The upper was mated to a Stag upper it had some teething issues with failure to cycle with Romanian surplus and light hammer strikes, I had to bored out the gas port a little bit, similar to the no. 4 setting on my XCR , swapped out the hammer spring a with a Wolff extra power one and haven't had a problem since.
    I am not an animal I am a human bean!

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