the one on the left looks longer but..it doesnt look like a 45 rounder so it maybe is just an optical illusion for me. it certainly doesnt bulge out like a 50 rounder and I dont even know of any 40-45 round mags for the ar?
after a quick google search and shitting the bread, I've realized, holy fuck there are 40 round mags for the ar.
right though? I've never even used anything but 20s-30s but you know, I'm also not mowing down mosque go-ers