The first AR15 carrier prototype is up. Most kydex mag carriers out there are built to run a single brand of magazine a single direction. My model currently runs Magpul Pmags and Lancer L5 AWM's rounds forward or rearward. Aluminum USGI's work rounds rearward, but will not insert fully. Smith and Wesson M&P 15-22 mags work ok as well, not enough to fight with, but probably well enough for the trainer purposes that the rifle lives for anyway. Retention is a little stiffer rounds forward but still within the range to be fully functional. The "nipples" pictured on the pistol and rifle carriers adds a third point of contact for attaching pistol magazines. This is about 75% to where I'd like to see it. Not perfect, but not bad for a first stab and close to the full function I'm looking for.