I have 2 steel 10's and one circle 10 in a 10. Now back when Tapco would sell the follower for 5 or 10 rds for the small mag. I have seen 30's cut down and with the steel mag it is easy so a 15rd mag is no problem. I also have 3 bulgy 10rd .223 mags for the SAR3.

Somewhere out in the garage is a bakelight 74 mag that I cut to 10 or 20 and modded it to .223 years ago.