This invention relates to firearms, and more particularly to methods and apparatus for installing a fixture such as a flash suppressor to the threaded muzzle end of a firearm barrel.
The suppression of muzzle flash and the reduction of muzzle lift upon the firing of a bullet from a firearm are conventionally implemented by a vented fixture fixedly secured to the firearm's muzzle end. In a commonly utilized type of fixture, functioning as a flash suppressor as well as a muzzle brake or compensator, the vent is provided by an odd plurality of longitudinal slots through the wall of the generally tubular fixture or flash suppressor. It is well known that the flash suppressor should be affixed to the firearm's muzzle such that the middle slot (i.e., the rotational center of the vent) is at top dead center (i.e., at the 12 o'clock position) with respect to the longitudinal axis of the firearm barrel.
In one manner of installing a fixture such as a flash suppressor to the threaded muzzle end portion of a firearm barrel, one or more shims are placed about the barrel's threaded muzzle end portion and between the barrel's forwardly facing annular shoulder situated rearwardly of the barrel's threaded muzzle end portion and a rearwardly facing shoulder of the flash suppressor situated rearwardly of a threaded bore of the flash suppressor. The flash suppressor is fixedly secured to the barrel when the correct shims are in place and a predetermined torque is applied to the flash suppressor with respect to the barrel, resulting in the flash suppressor's middle slot being fixedly positioned at top dead center.
Before the present invention, the appropriate shims were selected by a trial and error repetition of steps. The installer would thread the flash suppressor onto the barrel's threaded muzzle end portion hand tight, whereupon the installer would note the rotational location of the middle slot. If the middle slot is not at top dead center when the predetermined torque is applied to the flash suppressor with respect to the barrel, the flash suppressor is unthreaded and removed from the barrel. One or more shims are selected and placed onto the barrel's threaded muzzle end portion, whereupon the flash suppressor is again threaded onto the barrel's threaded muzzle end portion and the predetermined torque is applied to the flash suppressor with respect to the barrel, and the rotational position of the middle slot is again noted. If the middle slot is not at top dead center, the flash suppressor is again unthreaded and removed from the barrel, shims are added to or subtracted from the barrel's threaded end portion, the flash suppressor is again threaded onto the muzzle end portion and the predetermined torque is again applied and the rotational location of the middle slot is again noted. These steps are repeated until the middle slot is at top dead center.