Smith & Wesson M&P - Design Details

Design Details

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.

The pistol frame is made out of Zytel polymer reinforced with a stainless steel chassis. The slide and barrel are made out of stainless steel that after through 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.

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 and Wesson classifies the M&P's action as "striker fired (double action only)".

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_f). The M&P45c models have a slightly higher rated trigger pull of 31 N (7.0 lb_f). The competition oriented M&P40 Pro Series have a reduced trigger pull of 20 N (4.5 lb_f) due to the installation of a Smith and Wesson performance center sear. Massachusetts (MA) approved models have a trigger pull of 45 N (10 lb_f).

Several safety features are prominent on the M&P. A sear deactivation lever permits the shooter to disassemble the pistol without having to pull the trigger to accomplish disassembly. The pistol also has a loaded chamber indicator viewing opening on top of the slide.

Ergonomics were a key focus in the design of the firearm, and as a result, three interchangeable palm swell grips are included (small, medium and large). The trigger guard is designed to accommodate gloves. The frame of the M&P has a slide release lever on each side. The magazine drops free when the magazine release is pressed. The firearm features an ambidextrous slide stop and reversible magazine release for either right or left hand operation.

The pistols are delivered with 2 magazines.

The standard iron sights are of the three dot type and made of steel. Both the front and rear sights are dove-tailed into the slide, and can be horizontally drifted to adjust for windage correction.

An integrated Picatinny rail can be found underneath the slide on the front of the frame for attaching tactical lights, lasers and other accessories.