The B&T MP9 was developed directly from the Steyr Tactical Machine Pistol (TMP). The original TMP design was designed by Steyr in 1989 and B&T obtained the rights to the patents, drawings, and production of the TMP in 2001. A further redesign of the weapon after input from probably users resulted in the B&T MP9 in 2004. All specifications above are for the B&T model.
Over 80% of the MP9, including the receiver and major components, are produced from a high-impact polymer resin, a Nylon 6 Polyamide variant. This helps keep the overall weight of the weapon very low. An empty MP9 without an Aimpoint sight weighs less than three loaded 30-round magazines for the weapon. The primary changes from the original TMP design are the addition of an integral folding stock along with an integrated 13 cm (5.12 in) long MIL-STD 1913 Picatinny top rail. Additional sections of MIL-STD 1913 Picatinny rail can be added to the front side of the receiver to meet the users demands.
The operating system of the MP9 is based on a locked breech firing from a closed bolt. The locking system is rare in that it has a cam-operated rotating barrel. When the recoil of firing drives the barrel and slide back, a cam rotates the barrel slightly, unlocking it from the slide. Then simple blowback operates the weapon through its firing cycle. With no gas system to operate the locked breech, the MP9 is a very clean weapon to fire. The integrated vertical front grip allows the weapon to be controllably fired with both hands when the stock is folded. The same grip allows for a very firm hold when firing the weapon with the stock extended.
The charging handle is at the top rear of the weapon where it can be operated with either hand. The manual safety/selector switch is also duplicated on both sides of the weapon. Though the MP9 is fitted with simple iron sights, it is recommended for use with the Aimpoint Micro TL single point sight. The QD (quick detachable MP9-N Suppressor can be added or removed to the three-lug muzzle attachment in a matter of seconds.
For undercover operations, to include close protection of VIPs and surveillance, a Discreet Carrying & Firing Bag was developed for the MP9. The bag allows a fully-loaded, suppressor equipped, MP9 to be carried inside the bag, completely hiding it from view. An operator can slip his hand into the bag and either quickly draw and fire the weapon, or simply shoot the MP9 through the side of the bag. A brass catcher can be attached to the weapon so that empty brass will not interfere with the weapon being fired while under cover.
