Never used it in a Mac, but didn't work well in the Uzi. Some of the cases stuck in the chamber and had to be pounded out. Even had a squib load get stuck midway in the Beretta 92. Had to pound the slug out. Just glad another didn't get stacked behind it. I'll shoot up what I have and never buy any more. And I'll jump in any time I can to tell others how bad this stuff is. I can't believe they even sell it. Hope there hasn't been any injuries with the stuff.
CM