The .45 is famous for being the bullet used in the M1911 and for being the choice of the U.S. Military for their pistols for almost 75 years. The .45 ACP has good stopping power because of the large size of the bullet, a .45 ACP bullet is almost half an inch. When shot at human targets, the .45 ACP bullet makes a big hole that causes blood loss and leads to faster death. 