Gun Toter is correct. Refering to my Colt Manual, Second Edition, 1988, page 36; "Initial torque applied to the barrel nut shall be 30 lb-ft using torque limiting wrench and the combination wrench and with the barrel held in the barrel removal vise jaws, in a bench vise. Additional torque shall be applied as nessesary to create clearance for free entry of the gas tube through the barrel nut,...."
Strike Hold