At S2H classes this year we saw multiple Waters, NDR, factory, AICS and Mamba mags used extensively.
Factory 223 mags:
Depends on the mags. Some work excellently, some do not. When tested correctly in each rifle the 4 round mags work well.
Water T3 223 mags- plastic follower:
Worked very well until rain and sand/small debris got in. Afterwords, the follower would fail to rise relatively often. (Note: the M595 water snags have a metal follower and have functioned perfectly through all weather and conductions).
NDR 10 round 223 mag:
Nearly same as the Waters- plastic follower. Generally worked very well until rain with sand/small debris then the followers would lock up in the mag. Also, the two I have will malfunction with the first round when loaded to a full 10 rounds.
AICS 223:
Variable. Some models worked well in some guns, but the same mags were disasters in other “identical” rifles. Same for other models. When mags are well matched and tested for individual guns, they work ok. Overall, the most inconsistent option.
Mamba 10 round mags:
Functionally flawless in all conditions, across nearly 100,000 rounds and 60+ rifles. Not the smoothest feeling during feeding, but function is spectacular.