Factory The Smith & Wesson M&P22 Magazine is a standard factory replacement magazine. This magazine is for M&P22 Compact pistol models chambered in .22 Long Rifle and holds 10 rounds of ammunition. The Military & Police (M&P) magazine is made of steel and polymer and is made to Smith & Wesson's specifications and tolerances, using the same manufacturing and materials as the original equipment magazines to ensure perfect fit and operation.