45 Hole ammunition was Specially made for Glock and "GAP" basically means "Glock Automatic Pistol". Engineer Ernest Durham designed the forty five GAP round as being a cartridge that may be as highly effective as 45 ACP but would have a more robust situation head to reduce the prospect that https://tacticalrounds.com/product-category/handgun-ammo-for-sale/45-gap-ammo/