Sunday, August 08, 2010
As can be seen this covers improvised sound suppressors, and component parts of a sound suppressor. There is no thresh hold level of sound reduction for something to fall under this definition. ATF used to require the device "appreciably" lower the sound (see Revenue Ruling 57-38); now the working definition seems to be anything that traps gas from the muzzle of the gun, or from porting of the barrel, is a sound suppressor. In general recoil compensators and flash hiders do not fall under this definition, but some designs could fall into the category. As with any borderline device the thing to do is to get a written opinion from the Technology Branch of ATF. It is what they exist to do.
-magpul ubr
The Magpul UBR (Utility / Battle Rifle), U.S. Patent 6651371, is a fully-featured, adjustable butt stock for the AR15/M16. Unlike typical collapsing stocks, this modular design offers the stability of a fixed stock with consistent cheek weld in any position. Seven-position length-of-pull (LOP) adjustment is quickly executed with gross motor movement while the integral preset system allows direct access to a preferred position. A robust lock mechanism and multi-shell construction increase durability under severe impact conditions experienced during malfunction clearing and accommodates large-bore AR calibers with ease. The UBR also provides extra counterbalance weight to improve handling on full-length rifles and weapons with muzzle-heavy accessories or bull-barrels. Optional components such as dual-side sling mounts and metal strike plate allow the UBR to adapt to the mission at hand.
