The Shield 40 and 9mm are identical in all ways except for the barrels, slide opening at the sight hole, and markings on the slide. They both have the "new & improved" trigger action. When the Shields came out in April, S&W told several magazines and gun television shows that they would eventually incorporate the Shield trigger action into the rest of the M&P pistol models. The Guns & Ammo advertisement states “Positive, Tactile Trigger Reset." So hopefully all M&P pistols will be shipped with the new & improved trigger action.

Bob