Update:
Well I filled an old plastic pill bottle that was the right diameter for the muzzel brake and long enough with urethane resin and let it cure over night. I then drilled a hole down the center of the cylander of resin, inserted a bolt and locked it with a jam nut, then chucked it in my drill(poor man's lathe) then turned the outer shape of the muzzel brake. When satisfied with the shape I then drilled out the bore diameter and then cross drilled the vent holes. Here are pics of the muzzel brake snug fitted to the end of the barrel......Harold