MEASURING FOR SCREW-IN CHOKES (Shotgun)
Before accepting a barrel for machining to accept screw-in chokes, you must measure the outside diameter (O.D.) to determine if there will be sufficient wall thickness after machining. “Mike” the O.D. of the barrel and the O.D. of the tap for the particular gauge. Subtract the O.D. of the tap from that of the barrel,…