I have two 20 rnd mags for prone shooting and it is now starting to annoy me. I'm having some problems when I use them on either of my AR-15 carbines. Sometimes it fails to extract, sometimes a new round is and spent round is stuck in upper reciever, etc.
I have not had any mechanical malfunctions with 30 rnd magazines (a few but thats because of my fault) but I had some stoppages and I'm starting to wonder if I can trust this mag in SHTF situations or under certain combat training. No both of 20 rnd mags don't have green anti-tilt followers.
All I did was to thoroughly clean them around follower and magazine inside and outside, but I did not disassemble it in fear of faulty assembling it. I have no idea what is the problem - is it follower? is it spring?
Not positive, but assuming when you state "fails to extract" your actually meaning fails to feed (or that round fails to leave the magazine).
Sounds like feed-lip problems, how old are these mags?
BTW, alloy mag followers are all you'll find on 20 round mags, as green followers require modification in order to work in 20 rounders.
Suggest ya purchase 1 good 20 rounder from somebody like GPSS (Georgia Precision Shooting Supply) on-site here (Industry forum or EE), then when it arrives you can compare lips and assembly with a good one. I have heard of mag springs getting reversed on follower and causing problems, but generally speaking 20 rounders are far more reliable than the 30s.
Suggest ya do a complete disassembly on the problem mags to check springs and thoroughly clean inside of mag bodies.
Hope this is some help,
I have Colt 20rd mags with black plastic followers and USGI 20rd mags with alloy followers that I've been using for the last 15 without any problems. Do what Mr. Wilson stated in his post and compare the problematic mags with others.