Yep, G21 is only 10% larger but you get 13+1. With a GAP you're giving up 3 rounds and as tests have shown any major caliber pistol cartridge is about as effective as any other so if you're going to go with a G17 size gun then why not just get the G17 and have 17+1 rounds of 9x19mm+P on tap.Holy cow! TNFrank I have 2 G21's and never paid attention to magazine capacity on GAP models. Another reason to not get one.
GAP mags are the same size as the 9/40 mags. The feed lips are wider, of course, but the GAP is smaller and for many of us, it's easier to handle than the ACP in Glocks. Even with the SF frame, they're too big for my hands.The G.A.P. is a blind spot with me. Do the G.A.P. Magazines measurements differ from .45 ACP Magazines?