A 45 GAP Glock is basically a large frame Glock slide on a medium Glock frame. It was introduced because the large frame Glocks are too big for people with smaller hands (like female police officers) so the solution Glock came up with was to use the smaller G17/22 frame with a slide that would accomodate a large calibre round. The down side with the idea iss that the smaller frame can't accomodate a double stack 45 ACP size mag so they had to go with a single stack mag that only holds 10 rounds. Ballistically the 45 GAP and 45 ACP are very close. The advent of the Gen 4 Glocks with assorted size backstraps pretty much made the 45 GAP concept redundant.
That being said, there is absolutely nothing wrong with the calibre or gun. Unlike some dead cartridges with proprietary components like the 41 Action Express (which was a good cartridge and just as effective as the 40 S&W), if you reload 45, component availability will never be an issue. The gun can use any standard 45 ACP bullet. Cases are available (Starline makes them) or you could always trim down 45 ACP cases. The 45 GAP cases use small pistol primers but large primer 45 ACP cases will work. If the primer size bothers you, small pistol primer 45 ACP cases like Blazers would work fine. 45 ACP reloading dies work as well.
I have two 45 GAP pistols, A Glock 37 and an Springfield XD. Both are good guns and I got them dirt cheap so. I reload so the potential scarcity of commercial ammo didn't bother me. If we could carry, either one would be a good choice as a lighter, large calibre self defence gun.
