Appendix E2 · pages 117–117
Compensator Measurement

The proper way to measure the length is:
The 3.00” measured length on a compensator, is measured from the end of the muzzle of the barrel to the end of the comp with the comp attached, as shown in the above diagram. This can be accomplished without removing the compensator by placing a pen or pencil into the end of the compensator until it stops at the barrel.