I've had a few magazines just not work. It's like there's no friction at all, the bullets just come out without any effort. I had this happen with a couple of AR magazines, a Promag AK magazine, and lately a SGM 26 round magazine for my new Ruger LC in .45, which is a Glock knock off. Oh, Glock doesn't make a .45 magazine with 26 round capacity. It's either SGM or KCI. Glock does make the .45 magazine with a 13 round capacity, however the weapon came with a SGM 13 round magazine. Before this I had a bad Ruger mini 14 magazine with 30 rounds and I mailed it back in and they sent me another one. It had the same issues.
The latest magazine in question would be the .45 SGM 26 rounder. The gunsmith at Marksman range even took it apart, oiled it down, and replaced everything, and it's still a paperweight.
So, is this common to have an occasional bad magazine out of the box, that just needs to be put in the trashcan.