Tested in the military as a machine pistol and in competition environments as semi-automatic pistol caliber carbine (PCC)!!
United Defense Mfg Corp’s S9-DBB model semi-automatic carbine is a pistol caliber carbine inside an AR-looking rifle chambered in the time-tested 9mm NATO round (9x19mm) and designed to hit point targets up in excess of 150 meters. The S9-DBB semi-automatic carbine of United Defense takes after the AR-looking rifle designed by Eugene Stoner but using the 9mm Glock magazine and other after-market 9mm Glock-style magazines. It uses the very simple delayed blowback system influenced by the design of Ferdinand Mannlicher in earlier years. In this design, the breech block is delayed after the round is fired to make sure that the ammunition cartridge is fully supported while under high gas pressure.
UDMC did not design the system using the rotary or roller delayed blowback as it believes it is unnecessary, adding more moving parts that will be subject to wear and tear while the weapon is in battery. “Blowback is a system of operation for self-loading firearms that obtains energy from the motion of the cartridge case as it is pushed to the rear by expanding gas created by the ignition of the propellant charge.” The S9-DBB model uses a one-piece KeyMod picatinny rail handguard held securely only at the barrel extension which allows the barrel to “float” and preserve barrel harmonics while in battery. This allows for greater accuracy and consistency. As designed, the barrel does not touch any part of the entire length of the handguard except at the barrel extension.
The barrel comes in different lengths: 7.5, 10.5, 11.5 and 14.5. For special orders, UDMC can produce a lightened model that will reduce weight by another 15%. The barrel is stainless 416R premium barrel made by UDMC from Bergara cylindrical blanks. The bolt has an “open bolt” feature after the last round is fired.
Classification - Pistol Caliber Carbine Service History - Designed and Launched in October 2019
Manufacturer - United Defense Manufacturing Corp, Philippines Operating System - Delayed Blow Back
Bolt Group – Made of 8620 steel, one piece body Cartridge
9mm NATO (9 x 19mm) Barrel Type - stainless steel 416R premium
Barrel Length - 7.5 inches Rifling
1 x 16 (Semi-Automatic Carbine)
Muzzle Velocity - Approximately 1,100 to 1,200 ft/sec using the 115 grains FMJ ammunition
Maximum Effective Range – in excess of 150 meters point target
Accuracy (grouping) - Maximum of 1.5 MOA using combat load 115 grains FMJ ammunition. Tighter groupings can be achieved using match ammunition.
Trigger - Single stage with a trigger pull averaging 4-5 lbs.
Flash Hider - Shuriken low flash