...and it might as well fit in an AR magazine while we're at it.
Take a look at the ASC AR-15 mags. They are powder coated stainless steel and will allow for seating out to 2.315" vs standard 2.250".
ASC LINKI have both 20rd versions and 30rd versions of these and have had no problems with them at all. Well, except when one fell out of the truck and got run over...
Ed