I just read on another forum where someone cut down the M4 feed ramps on an AR to improve the 7.62x39 feed and reliability on an AR47 (AR that fires AK food or 7.62x39). As an owner of numerous AR47 rifles and pistols, I offered my solution and then realized that I should post it here too. So here it is, just in case anyone here has similar issues when building a quality AR47, since the steel 7.62x39 round is relatively inexpensive when compared to other rounds.
I have numerous ARs chambered in 7.62x39, both pistols and rifles, and they all run flawlessly without any modifications to the feed ramps. Although I experienced similar failure to feed issues and could see scratches to both the bullet and casing in my early builds, I determined that it was the magazine feed exit point cut in the magazine that was inadequate. The same poor design was on all 7.62x39 mags I tested.
As many others have noted, a simple modification to the magazine is a typical fix. To date, I have "dremeled" over 40 mags, like the one below, and the issue, at least for me, has been resolved.
If you look closely at the top of the left "un-dremeled" mag in the picture below, you can see that the top "ready to feed" round is almost perfectly in line with the mag exit point (although my camera angle makes it look slightly above the metal), meaning that the bullet and steel casing have a very high probability of snagging the mag upon exit, thus leaving the scratch/gouge on the bullet and casing, also resulting in a potential mis-feed angle.
For the "dremeled" mag on the right, the "ready to feed" round is well above the mag exit point, thus allowing free exit with no restriction in feed. After trying many mag brands, the 28-round C-Products Defense is what I try to buy, as the 28-round fits better in most mag pouches (less of a curve in design) and is easy to Dremel to give me the same positive feed results.
I have numerous ARs chambered in 7.62x39, both pistols and rifles, and they all run flawlessly without any modifications to the feed ramps. Although I experienced similar failure to feed issues and could see scratches to both the bullet and casing in my early builds, I determined that it was the magazine feed exit point cut in the magazine that was inadequate. The same poor design was on all 7.62x39 mags I tested.
As many others have noted, a simple modification to the magazine is a typical fix. To date, I have "dremeled" over 40 mags, like the one below, and the issue, at least for me, has been resolved.
If you look closely at the top of the left "un-dremeled" mag in the picture below, you can see that the top "ready to feed" round is almost perfectly in line with the mag exit point (although my camera angle makes it look slightly above the metal), meaning that the bullet and steel casing have a very high probability of snagging the mag upon exit, thus leaving the scratch/gouge on the bullet and casing, also resulting in a potential mis-feed angle.
For the "dremeled" mag on the right, the "ready to feed" round is well above the mag exit point, thus allowing free exit with no restriction in feed. After trying many mag brands, the 28-round C-Products Defense is what I try to buy, as the 28-round fits better in most mag pouches (less of a curve in design) and is easy to Dremel to give me the same positive feed results.