Brownells TAP 1'' DIA, 1/4''-18 TPI FOR AR-15/M16 DWTST1-3/16-16P

Chases and cleans the two most important threads on the AR-15/M16 receivers. 1.250''-18 tpi - Corrects out of spec or cross-threaded upper receivers and barrel nuts. 1-3/16''-16 tpi - Makes receiver extension (recoil buffer) tube and lower receiver threads uniform for easier installation.