These are running fine in my 450 bushmaster. - Duramag SS AR-15 .458 SOCOM/.50 Beowulf 10 Round Rifle Magazine

I've bought a few of these now for my 450 Bushmaster. I'm running a Spikes lower with carbine collapsible stock and Spikes buffer. Upper is a Bear Creek Arsenal. No feed problems and fires and ejects right to the last round. I did not round off the front of the magazine as some have. Its still flat across and maybe in the future I may take out the Dremel. But for now I 'm good. Like the magazine and for the price you cannot go wrong. I have modified a few standar AR 556 mags, but I think this is a better choice. JMHO.