i have 3 profiled 158 toppers: 1- AA/USPatent 2-AD/USPatent 3-AF?Serial#... all that i have, 2-30/30 and 1-22jet, as well as any parts/barrels for profiled that i've seen are all snap-on forend. only exception was an obvious/ poorly done replacement with screw spud. not all that experienced on these, just what i've seen. regards, jather........