[AuroraUnit117]

Hmmmm. It could also be the feed lips are bent, so that when you pull it back it causes resistance. Or it could be the gasket is so high up it is pushing on the nozzle. So what youre saying is that it will fire, but it wont blow back, and when you pull the slide back it has alot more resistance then the other mags? I would check the top pieces of the new mags and see if maybe they werent installed properly and are sticking out more then your old ones. But the feed lips could be grabbing the nozzle causing issues, i had that happen with my M9 once, it wouldnt blow back all the way and i just filled down the feed lips and smoothed them and it fixed it.