SOLUTION - standard AR mag modified for 50 Beowulf 

The polymer magazines are shit mine does the same thing I can only load two rounds in it maybe three once I add the forth it vomits every last round out. I’m looking into steel magazines because I noticed that the polymer magazines lips like flare out so the magazine is not tight at the lips and any little bump all the bullets are on the floor.

@@eidtnaci I'm in NY so the mag must be pinned in place so you only get one shot at getting it right. Was hoping for a true 10 rounds. Steel doesn't give you that option that I am aware of. 20 round steel will get you 7 and 30 is too much hanging out there for me. Oh well.

Strangely enough the big bore magazines (.50 Beowulf, .450 Bushmaster and .458 Socom) don’t seem to have the relief cut like I am doing here. I think they must use a different follower angle and/or different angle of the feed lips to accommodate and “steer” the larger round into the chamber. On a standard AR mag a person may have good luck, but my experience is like yours…rounds either shoot out of the magazine like an expensive jack in the box, or they jam up during feeding and scratch the hell out of your brass. So far this is the best and lowest cost solution I have found to reliably feed these huge rounds.

It should. I would be a little worried about bulging of the polymer at the feed lips, but magpul does have a better polymer than the other one I tested. I think you should be good to go.

@@SMR-Tactical thanks. Didn’t know if i needed to change the follower or not. 💪🏽

Ahhh, I see. I don’t believe the follower would need to be changed. Should be good with the one that comes in there.

It’s called tolerance stacking. If yours work without issue, you are lucky indeed. But depending on the tolerances of the parts used, one may or may not have the same experience. I tried PMAG’s and Bulgarian Steel AR mags, and they just didn’t work quite right for me. Once the Bulgarian AR mags were modified as shown in the video above, I have had zero issues. Thanks for watching!

@@SMR-Tactical mine are original Colt mags from the 80's,and yes I agree for the most part it's about tolerances but that is with anything

Runs great, no issues. I bought a cheapie upper from Bear Creek Arsenal and have had no problems with it. Now in fairness, it hasn’t had 1000’s of rounds through it due to the cost of ammo for this one….but what I have put through it has had no failures in feeding, ejecting, firing, etc…. No issues at all.

Bear creek's big bore line is mostly fine, the barrels are really well built however the only concern is the BCG extractor but you can buy a stronger 7.62 one. Their firing pins also have issue but I think swapping for a titanium one with a big bore round is a good idea