Make & Install Custom Compensators For Reduced Recoil And Better Control
Use die to thread custom and standard barrels to accept recoil compensators. Use plug tap to chase threads or tap your own custom compensators. Unthreaded comps should be drilled with 3-5/64" HSS drill then reamed to .551" before threading with either tap. Turn barrels to approximately .002" smaller than thread diameter. .575"-40 thread matches most commercial, tapered-sleeve or integral, cone-style comps. .581"-40 thread is same as used on Wilson, Brown and Storm Lake Machine barrels and bushing style comps. .685"-40 thread is used to fit compensators to threaded Bull and Hybrid barrels.
1911, Issue:10, Page:061
Big Book Catalog, Issue:66, Page:145