For your .40 caliber Smith & Wesson, go with the Magnum Research Baby Eagle 12-Round standard factory replacement magazine. Whether you have a full size or semi compact, this magazine works for both models. It has been manufactured with a capability to hold up to 12 rounds of ammunition. It features a steel baseplate and it is made from steel tube giving the end user something they can feel proud of.
******NOTE: THIS MAGAZINE WILL NOT FIT THE WALTHER PPQ OR THE MR EAGLE