What does wmr mean pertaining to 22 cal?

WMR stands for "Winchester Magnum Rimfire," referring to the .22 WMR cartridge, which is a rimfire cartridge designed for rifles and pistols. It is more powerful than the standard .22 Long Rifle, featuring a larger case and a heavier bullet, making it suitable for small game hunting and varmint control. The .22 WMR is known for its increased velocity and range compared to the .22 LR.