Does anyone know anything about this? I have one I am holding for someone and would like some more info. other than what the S.A. site has to say. I have never even heard of this ammunition.
The .45 G.A.P. (Glock Action Pistol) cartridge was created back in 2003. Glock models 37, 38 & 39 use the cartridge. The bullet is the same bullet used in the .45 ACP. The brass is different. The case length is the same as the 9mm. The brass is thicker at the bottom and you can NOT cut down .45 ACP to make the GAP. The GAP also uses a small pistol primer.
The Glock pistols use the same size frame as the Glock 9mm with a 10 round capacity magazine.
The GAP has been adopted by several police agencies, so far mainly on the east coast. I believe Florida State Troopers are the next in line to get the GAP.
After owning a G17 (9mm) for 15 years, I wanted to move up to a .45acp pistol. But in order for Glock to build a pistol (G21) with a "double/large capacity" magazine they had to make a larger frame than they had used on the 9mm, 10mm, or .40 models. The G21 never felt that natural in my hand.
They desired to create a .45 pistol in a smaller frame. They started by designing (or more correctly commissioning) a new bullet that would have a shorter casing than the .45acp. This would allow them to build smaller magazines that would fit into a smaller frame. The ballistics of both the acp and gap are practically the same.
I looked real hard at purchasing a G37 (.45gap). But each time I went looking for one the dealer cautioned me about the availability of ammo. It is still hard to find, and is more pricey than .45acp.
Then Springfield came out with their XD45 were they stretched the laws of physics, and got the .45 acp into a smaller frame. I haven't looked back since.