A few weeks ago I bought a AR15 in 50 Beowulf from a freind, I have had it to the range twice and both times I had some problems with feeding from the magazines. The other day it was better but I noticed with the Polymar80 mags I got that were labeled for the 50 had two problems. The first was the magazine would bulge with 10 rounds in it (standard 30 round design), and the first round would load and fire but the second would hang up and the case may not eject. The solution for me will be these will now be 8 round mags. The second problem is that the mag follower plate is the standard AR stepped plate and the last round had a tendency to become wedged into the step and not be in position to be loaded. Today I took one of the mags apart and built up a form with some duct tape and filled the follower flat with some epoxy. I will be able to file and sand the epoxy in a day or two and see if that solves the problem.