The question of velocity in .45 ACP cartridges is critical for understanding their performance. Standard pressure .45 ACP ammunition typically features muzzle velocities below the speed of sound (approximately 1,125 feet per second). However, +P loads, designed for increased performance, can exceed this threshold, making them supersonic. Therefore, not all ammunition manufactured for this caliber is subsonic.
Understanding whether a given .45 ACP load is subsonic or supersonic has practical implications for several reasons. Subsonic ammunition generally produces less noise, especially when used with a suppressor. It can also offer different recoil characteristics. The historical development of the .45 ACP cartridge, originally designed for stopping power, often focused on heavier bullet weights at lower velocities, contributing to the prevalence of subsonic loads. However, modern advancements have allowed for a broader range of bullet weights and velocities, making supersonic .45 ACP an available option.