For some reason, I used hyper velocity LR in my example. Standard velocity .22 rimfire ammunition are cartridges with muzzle velocities between 1055 fps and 1100 fps.
Subsonic ammunition has a muzzle velocity under 1055 fps, or under the speed of sound measured at sea level. In a subsonic cartridge, the shooter does not experience the high pitch "crack" that is common with high velocity ammunition. The "crack" is actually the bullet breaking the speed of sound and producing a small sonic boom.(liberal plagiarism from the website)
About 825 fps from an Astra *Cub* model 2000 with a CAC22 sound suppressor on it, firing CCI standard velocity .22 short target ammo loaded for Olympic rapid-fire competition, often shot with the short cartridge, considerably less powerful than most .22 short ammo other than the CB cap loadings.
About 825 fps from an Astra *Cub* model 2000 with a CAC22 sound suppressor on it, firing CCI standard velocity .22 short target ammo loaded for Olympic rapid-fire competition, often shot with the short cartridge, considerably less powerful than most .22 short ammo other than the CB cap loadings.