Designed by John Browning in 1904, the .45 ACP is an effective combat pistol round, combining accuracy and stopping power. Used in the Colt .45 pistol, the .45 ACP round was used by the US Army in 1911. The ACP stands for Automatic Colt Pistol, the .45 ACP is known for having low muzzle flash and blast and moderate recoil. Maine Ammo Company stocks a wide range of 45 ammo to satisfy the needs of plinkers, hunters, competitive shooters, and the avid ammunition aficionado. Being avid shooters ourselves, we enjoy trying out new 45 ACP ammo and try to offer you 45 ammo at very aggressive prices so that you can share in our most favorite pastime. when in a Maine Ammo store or online, ask about our 45 ACP “bad boy” round. This 45 ACP round will shock you.