I researched the question of a muzzle device for a 6x45 AR I built with a 1/2-28 threaded muzzle, but found no satisfactory answers on the interwebs including the BHW the barrel mfg. Until I found http://www.precisionreflex.com. Who had a 1/2-28 to 5/8-24 thread adapter. Now my 6.8 muzzle device fits like a champ.