RWS Subsonic HP 22LR

The RWS SUBSONIC HP is a special cartridge for
low-noise shooting. The bullet velocity stays distinctly below the
sound barrier – consequently there is no sonic boom. For this reason,
this rimfire cartridge is
very well suited for weapons with silencers. It offers similar good
shooting performance as a standard cartridge, but with significantly
less noise. Due to the hollow tip, this ammunition achieves a sure and
reliable effectiveness with small game and varmints.
Not suitable for selfloaders!

– See more at: http://rws-munition.de/en/hunting/products/rimfire-cartridges.html#!18/261/0