United Defense Mfg Corp’s S9-DBB (commercial or civilian semi-automatic model) is a pistol caliber model inside an AR-looking rifle chambered in the time-tested 9mm NATO round (9x19mm) and designed to hit point targets up to 100-120 meters. This S9-DBB model of United Defense take after the AR-looking rifle designed by Eugene Stoner but using the 9mm Glock magazine and other after-market 9mm Glock-style magazines. The S9 (and its brother F9 military sub-machinegun model) uses the very simple delayed straight 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, specially on full-automatic mode.
“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.”
Both the F9-DBB and S9-DBB models use 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 fluted barrel does not touch any part of the entire length of the handguard except at the barrel extension. For both models, the barrel comes in different lengths: 7.5, 10.5, 11.5, 14.5 and 16 inches. For special orders, UDMC can produce a lightened model that will reduce weight by another 10%.
The barrel is fluted, non-glare, matte finish, using the SS-410 stainless steel or 4150 carbon steel barrel made by UDMC from Bergara cylindrical blanks, and IS NOT CHOOSY WITH ANY BRAND OF AMMUNITION. It works very well with the Philippine-manufactured Armscor 115 grains 9x19mm ammunition!
The following features are not to be taken for granted when comparing with other designs:
1. The S9 uses a Bergara SS-410 fluted match barrel versus ordinary carbon steel barrel.
2. The S9 uses a ONE PIECE bolt and bolt carrier versus two pieces and it has an "open bolt" feature after the last round is fired. This OPEN BOLT feature is a very important SAFETY feature and a huge advantage in fast reload situations. Yung tinatawag na "Last Round Bolt Hold Open" (LRBHO) is very important. Yung S9-DBB has that feature both for safety reasons and for fast reloads. Dapat bigyan ng halaga yang feature na yan ng mga buyers.
3. The S9 uses KeyMod monolithic rail floating handguard versus plastic non-floating handguard.
4. The S9 uses Ambidextrous charging handle with a left and a right latch versus the ordinary left latch only.
5. The S9 uses Ambidextrous safety selector a left and a right knob versus the ordinary left knob only.
6. The S9 uses a 2-chamber Compensator versus the ordinary flash hider. This compensator tames muzzle rise.
7. The S9 uses Flip-up front and rear sights versus the ordinary fixed front sights and a heavy rear sight on the carrying handle.
8. The S9 uses an H2 tungsten buffer versus ordinary light buffer that aids in a more reliable cyling.
9. In the S9, the cartridge is FULLY SUPPORTED inside the chamber with no possibility for the cartridge to rupture at the base of the ammunition shell.
10. The S9 looks aesthetically like an M4, a preference for some shooters.
11. Most of all, the S9 warranty is in the Philippines and not in a faraway country. How can the warranty of a foreign brand be fully supported if their manufacturing is not in the Philippines?
12. The bottomline is that our S9 is not cheap but it has a better "value for the customer's money". The key words are "VALUE FOR MONEY". So when comparing prices, you also have to compare functionalities, safety, reliability, accuracy, other features, accessories and overall design. Now if the above features and accessories are not important to you and you want a simple home defense 9mm rifle, let UDMC know and they will build one for you at a much less price. Again, the one posted above is NOT a home defense rifle. It is a competition PCC carbine.
Classification:
Sub-Machinegun (military model) or Carbine (commercial/civilian model)
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
Sights - Flip up sights, front and rear
Cartridge - 9mm NATO (9 x 19mm)
Barrel Type - Non-Glare, matte stainless steel barrel SS-410 (for competition shooting) or the black parkerized 4150 for the sub-machinegun.
Barrel Length - Choice of 5, 7.5, 10.5, 11.5, 14.5, 16 and 18 inches
Rifling - 1 x 10 twist (Sub-Machinegun) and 1 x 16 (Semi-Automatic Carbine)
Muzzle Velocity - Approximately 1,100 to 1,200 ft/sec using the 115 grains FMJ ammunition
Charging Handle - Ambidextrous
Safety Selector - Ambidextrous
Maximum Effective Range – 100 to 120 meters point target
Cyclic Rate of Fire – 850 rpm on average
Accuracy (grouping) - Maximum of three (3) MOA using combat load 115 grains FMJ ammunition. Tighter groupings can be achieved using match ammunition. Bullet drop varies according to barrel length, projectile weight and charge.
Trigger - Single stage with a trigger pull averaging 4-5 lbs.
Flash Hider - Compensator muzzle brake with two chambers.
Weight - Around 3.2 kg (16-inch barrel), inclusive of the floating KeyMod picatinny rail handguard and flip-up sights, without magazine. Weight will be less depending on barrel length.
Length - 32 inches (16-inch barrel)
Barrel - Fluted
Feed System - 30-round detachable magazine (Glock-style magazine)
Buffer – H2 type (same as the M4 buffer with tungsten weights)
Body Color - Anodized black
