Check the listing for details. 1/2x28 Barrel Shim Kit for .223 5.56 Muzzle Alignment Washer Set 14PCS. Color: Black, Condition: New. Listed at 20.92 USD. OD .748" & ID .511” Will fit .223 5.56 caliber barrel with 1/2x28 Thread Pattern Will NOT fit .308 Please check fitment before ordering. #Note# 1/2x28 barrel shim kit have two different OD available. OD .748” shim kit is designed for .223 5.56 9mm barrel with common .750” barrel OD. Special OD .625” shim kit is compact designed for some 9mm barrel with special OD (smaller than common .750") at the Min Barrel O.D.. Please check the fitment before ordering. will be an ideal and new solution for your device, whether you've tried the Thread Locker/Crush Washer/Peel Washer or not. Tips: shims can be used alone or in different combinations. This is just a game of trial and error to get your desired thickness.