It’s really a good idea to test all of your magazines out and not leave them in their new packaging. We recently had a recall on Magpul Generation 3 pmags after several Police Officers complained to us that they were not dropping free from their AR15 rifles. I personally asked them to bring them back in and tested them out myself in my LWRC M6A1. All of the mags I tested out hung on me and I went on AR15.com and found several people complaining about this on youtube.com and other places. Obviously Magpul was pumping out magazines without doing a very good quality control. I also found that several of the AK magazines I had for various guns I owned did not work in all of my AK rifles. Didn’t know until I pulled them out of storage on a range day.
Even if you are stocking up on pistol magazines you really should take them out of the rapper and do a quick magazine drop test. I own several 1911 pistols and various brands of 1911 magazines did not drop free but all of my Chip McCormick magazines did. Many competition shooters want longer base plates on their pistol magazines because they can grab them and pull them out while moving through a course. I’ve seen the look of shock on some first time IDPA shooters when had a gun on an angle or where using inferior “range mags” that weren’t there CCW mags. Don’t buy the cheap stuff because there are sometimes unintended consequences to buying second rate magazines.