The 7mm Winchester Short Magnum (also known as the 7mm WSM) is a centrefire cartridge developed in partnership with Browning Arms Company and Winchester ammunition, making its debut and introduced to the shooting public in 2001.
The 7mm WSM is similar to the .300 WSM and .270 WSM cases necked down to handle .284″ bullets. However, the distance from the casehead to the datum line on the shoulder is longer for the 7WSM, preventing accidental chambering or firing of the .284″ 7mm bullet in .270 WSM’s .277″ bore. Winchester claims a muzzle velocity (MV) of 3,225 ft/s with a 140 grain bullet for their 7mm WSM cartridge; the claimed muzzle energy (ME) is 3,233 ft. lbs. With a 160 grain bullet the Winchester figures are 2990 ft/s and 3176 ft. lbs. at the muzzle. The lighter, shorter 7mm bullets are preferred in these short case magnums.