This specific type of ammunition refers to cartridges loaded with projectiles designed for the .22 Winchester Magnum Rimfire (WMR) cartridge, featuring a velocity below the speed of sound. This typically results in reduced noise compared to supersonic ammunition. An example would be a 40-grain lead round nose projectile traveling at less than 1,125 feet per second.
Ammunition designed for reduced velocity offers advantages in several contexts. The subsonic characteristic minimizes the loud crack associated with supersonic projectiles breaking the sound barrier, which is valuable for noise-sensitive environments or when hearing protection is limited. This characteristic can enhance accuracy by mitigating the destabilizing effects of the sonic boom on the bullet’s trajectory. Historically, this type of round has been employed for hunting small game, pest control, and recreational shooting where noise reduction is desirable. The reduced report can also be beneficial for training new shooters.