5/8-24 Barrel Shim Kit is produced by Tacshim for 7.62mm/.308. These shims assist in timing and alignment, dependable design constructed and precision made from quality 304 stainless steel. Our shims Will Not adding unnecessary bulk of your barrel. Outer Diameter of .748" & Inner Diameter of .635" Compatible with 5/8" x 24 TPI Thread Barrel (7.62mm/.308) Kit includes .002”x 4, .003”x 4, .004”x 4, .008”x 4, .010”x 2 and .020”x 2 shims. 20 Pack Stainless steel shims of various thickness by Clearly Marked & Separate Packaged,so you can quickly identify thicknesses and save time. Will NOT fit .223/5.56 Tips: TACSHIM shims can be used alone or in different combinations. This is just a game of trial and error to get your desired thickness.