Patent ID: 7062874

Claim:
A method for installing a fixture to a threaded muzzle end portion of a barrel of a firearm having a sight rearwardly of the threaded muzzle end portion, the barrel having a forwardly facing annular shoulder rearwardly of the threaded muzzle end portion, comprising the steps of: providing a fixture including a generally cylindrical wall, an axial passageway having a threaded bore, a rearwardly facing annular shoulder rearwardly of said threaded bore, and a vent through said wall communicating with said passageway; providing a plurality of annular shims of predetermined thicknesses; providing a chart having an aperture for axially receiving said fixture, said chart including a sight alignment mark vertically above the center of said aperture, said chart including sectors about said aperture including indicia identifying shims for being interposed between said shoulders when said fixture is threaded onto the threaded muzzle end portion and a predetermined torque is applied thereto for rotationally positioning said fixture with the center of said vent substantially at top dead center, one of said sectors corresponding to no shims required being displaced from a chart location at a predetermined rotational angle from said sight alignment mark by a rotational displacement representing application of the predetermined torque; threading said fixture onto the threaded muzzle end portion of the barrel until said shoulder of said fixture is in contact engagement with the shoulder of the barrel; placing said chart to said fixture such that said fixture axially extends through said aperture and with said sight alignment mark rotationally aligned with the sight of the firearm; noting the identifying indicia in the sector to which a location on said, wall is rotationally aligned, said location on said wall being at said predetermined rotational angle from said center of said vent; removing said chart from said fixture; unthreading said fixture from said threaded muzzle end portion; selecting shims from said plurality of shims, the selected shims determined by the noted identifying indicia; placing said selected shims about said threaded muzzle end portion; and fixedly securing said fixture to the barrel when said fixture is threaded onto the threaded muzzle end portion with said selected shims interposed between said shoulder of said fixture and the shoulder of said barrel and with the predetermined torque applied to said fixture.