With the exception of the 12ga USH, all forends will fit including the syn, you may have to relieve the area just ahead of the chamber swell on the forend on the 20ga USH, I had to do that to fit the syn forend to my TDC barrel, the barrel channel itself should fit fine tho, forend channels are pretty generous, and they always can be sanded out with a sandpaper wrapped dowel.
Tim
