<P> The M&P is a striker - fired semi-automatic pistol . This trigger system prevents the firearm from discharging unless the trigger is fully depressed, even if the pistol is dropped . An internal lock and / or magazine disconnect are available as options and an optional external thumb safety became available in 2009 . </P> <P> The pistol frame is made out of Zytel polymer reinforced with a stainless steel chassis . The pistol comes with three removable and interchangeable grips . The slide and barrel are made out of stainless steel that after hardening is treated with a proprietary nitriding process called Melonite . The Melonite process produces a matte gray non-glare surface with a 68 Rockwell C surface hardness rating . The pistol has a very low slide profile which holds the barrel axis close to the shooter's hand and makes the M&P more comfortable to shoot by reducing muzzle rise and allowing for faster aim recovery in rapid shooting sequence . The slide has four contact points with the frame . This was done to make the rail system self cleaning, by leaving room for any dirt or small foreign objects to fall out of the weapon . </P> <P> As the slide of the pistol enters battery, the striker engages the sear . At this point, the sear is held back in a partially cocked condition . When the trigger of the M&P is pulled, the trigger bar first engages the firing pin safety plunger, lifting it upward, and releasing firing pin safety . At the rearward extreme of the trigger bar's travel, it engages the sear . The sear is rotated downward by the trigger bar, fully cocking, then releasing the striker . The striker makes contact with the primer of the chambered round, which in turn ignites the gunpowder and propels the bullet forward . According to renowned M&P gunsmith Dan Burwell, the angle on the rear face of the sear creates a camming action against the striker . This camming action moves the striker to the rear very slightly during the trigger pull, thus finishing the "cocking". This system is similar to the partially tensioned striker found in the Glock series of pistols . When the pistol cycles for the next shot, the striker will be automatically pre-set in a 98% cocked position . Because the striker is only 98% cocked prior to the trigger being pulled, Smith & Wesson classifies the M&P's action as "striker fired (double action only)". </P> <P> The M&P factory trigger is of the jointed type and has a trigger travel of 7.6 mm (0.3 in) and is rated at 29 N (6.5 lb). The M&P45c models have a slightly higher rated trigger pull of 31 N (7.0 lb). The competition oriented M&P40 Pro Series have a reduced trigger pull of 20 N (4.5 lb) due to the installation of a Smith & Wesson performance center sear . Massachusetts (MA) approved models have a trigger pull of 45 N (10 lb). </P>

M & p shield 9mm single action or double