Put Threaded Muzzle Brakes On Non-Threaded Barrels
Steel adapter allows you to install muzzle brakes and flash hiders on tactical rifles with an unthreaded barrel. No machining necessary; four setscrews secure adapter to barrel in seconds. C-5 Adapter has ½-28 threads for installation on Colt sporter and similarly contoured, AR-15 barrels.
AR-15, Issue:08, Page:016
Big Book Catalog, Issue:65, Page:016
New Product Supplement, Issue:571, Page:004
SPECS: Steel, blued finish. C-5 - 1-3/16" long, .708" (18mm) I.D., .978" (25mm) O.D. Fits Colt AR-15.