by Major Pandemic
Running the 7.62×39 in the AR-15 platform has gotten somewhat of a bad rap. Read through forums and you would think people are a little bi-polar, with one post saying they could never get it to work and the next post noting they bought one off the shelf or built one and never had an issue.
The most significant problem with the AR-15 format running AK-47 ammo has been feeding and functioning. There have been a lot of theories on what exactly is needed to make the round run in the AR-15, but usually it seems to come down to recommendations to start cutting on magazines.
Every possible problem I could have had with this build, I experienced. Nothing came easy. I placed an order with Delta Team Tactical for a $139 16″ 7.62×39 Melonite Barrel with a Carbine length gas system and their complete $139 7.62×39 Phosphate Bolt Carrier Group.
I plugged the barrel in a Anderson Manufacturing blemished $40 upper and a Parallax Tactical M-Lock forend. The only real high dollar components on the upper were a Fortis gas block and a Lantac Dragon comp to take the bite out of the heavier recoiling round. A Lucid red dot topped the upper, but it would be months before I was able to really get to using it. For the majority of testing I used my WMD Beast lower.
Once assembled, I ran to the range, excited to function test the build. Testing centered around the inexpensive ammo, with a couple steel cased Wolf and Cabelas Herter’s 7.62×39 rounds using Magpul Pmags and some C-product 6.8 SPC mags, which some had noted would work just fine if used with just a few rounds. They didn’t.
The upper would not feed more than one round at a time and even then seemed to jam the first round on the center of the M4 feed ramp. In many cases it would not even fully extract. When the gun did cycle, it was also short stroking big time and was nowhere near approaching the point where it would lock back on the magazine. Many have noted that you need a special firing pin, but at least with this standard Mil-Spec lower trigger, there were no detonation issues.
After the first time out, I realized the gun was way, way, way under gassed, with a far too small barrel gas port hole, I also needed a dedicated AR-15 7.62×39 magazine for testing and needed some work on the barrel’s feed ramps.
Many range trips later (test, fail, tinker, and repeat), I had polished the feed ramps to a mirror finish and drilled out the barrel gas port to a huge 1/8 (.125″) size, and suddenly the gun was locking back and at least trying valiantly to pick up the next round in the magazine. Jam city, even with the C-Products dedicated 7.62×39 magazine feeding FMJ, but I really could not fault the magazine. There was more wrong here than magazine issues and what my aggressive feed ramp polish would resolve. That split feed ramp was an issue.
This made sense because, due to the tapered case of the AK47 round. The round would angle toward the center of the feed ramp when the bolt attempted to pick it up, and guess what is in the middle. Yep, the split in the middle of the M4 feed ramps. So, I whipped out the Dremel and got to grinding away the split. Sure, I took a couple deep breaths before I basically trashed a perfectly good barrel extension, but in my mind it had to be done. It worked perfectly. In fact, now I can feed this upper with pretty much any magazine, but the C-Products dedicated 7.62×39 magazines delivered the best high capacity performance. I would expect any unmodified Stoner and ACS clone 7.62×39 magazines to deliver the same performance.
I have now put twenty full mags through this upper, running on a variety of lower receivers (including the WMD Guns Beast lower) and it has performed outstandingly. In fact, I have had zero functional issues in those 600 rounds other than the very occasional bad round, which is expected with inexpensive ammo.
Read more at alloutdoor.com
Photos courtesy of alloutdoor.com