The .45 ACP’s combination of stopping power and controlled penetration makes it practical for police use, although numerous issues, including the resulting decrease in magazine capacity and the larger size and weight of pistols chambered in this caliber, have led more police departments in the USA to adopt sidearms in 9×19mm, .40 S&W, and .357 SIG. Due to its large diameter and straight-walled design, the .45 ACP geometry is the highest power-per-pressure production, repeating round in existence. This is because of the higher powers achievable with .45 Super, and +P loads. With that said, it is obvious that the .45 ACP is an intimidating round. Popular firearms chambered in this round include the Glock 21, Heckler & Koch HK45, Springfield XD45 and the Sig P220.