Barrel nut assembly and method to attach a barrel to a firearm using such assembly
A fixture for use with AR15/M16 type firearms is provided herein. The fixture is made up of several parts that when used in conjunction with one another mitigate the transfer of torque from the barrel nut to the firearms receiver during barrel installation. The fixture affords the user a method and apparatus that holds the barrel in alignment with the firearm receiver and secures the barrel against rotational movement during installation of a barrel nut or similar device. The fixture may be configured to work with the legacy AR15/M16 type barrel nut, as well as other designs as disclosed herein.
1. A method of securing a barrel having an annular flange proximate to a rear end of said barrel, to a firearm using a barrel nut, a locknut and a fixture which is configured to receive a receiver of the firearm and the barrel nut and restrain both from rotational movement, the receiver having an externally threaded front end part which is configured to be threadedly engaged within a rear end of the barrel nut, the barrel nut having an internally threaded central bore that receives a chamber end of the barrel and a bushing with a bore therethrough which aligns with an opening located on a front face of the firearm receiver, the bore in the bushing and the opening in the front face of the firearm receiver being configured to receive a part of the firearm's operating system therein, the locknut being configured to slide onto and down the barrel and having external threads to threadedly engage with internal threads on a front end of the barrel nut bore, the method comprising the steps of:
threadedly securing the barrel nut about the externally threaded front end part of the receiver, the barrel nut being rotated at least one complete revolution, until the bore in the bushing aligns with the opening in the front face of the receiver;
securing the fixture about at least the receiver of the firearm and a portion of the barrel nut, said barrel nut having an external structure configured to engage with said fixture and prevent rotation of said barrel nut while torque is being applied to the locknut to secure the barrel to the receiver;
inserting the chamber end of the barrel into the barrel nut until the barrel seats into place against an abutting face on the firearm receiver and the annular flange is contained within the central bore of the barrel nut;
sliding the locknut down the barrel toward the chamber end of the barrel
and threadedly securing the locknut to the barrel nut by rotating the locknut until the locknut comes to rest against the annular flange on the barrel; and
tightening said locknut against said annular flange to a preset torque value.
2. The method of claim 1 , further comprising the step of using a vice to secure the fixture in place and prevent unintentional movement thereof.
3. The method of claim 1 , further comprising the step of using a wrench with a crescent shaped head having a plurality of teeth projecting from an inner periphery configured to engage with grooves formed on a forward face of the locknut, the wrench being used to rotate and secure the locknut against the annular flange of the barrel.