THESE BARRELS ARE MADE BY THE NEW THOMPSON CENTER, ROCHESTER NEW HAMPSHIRE. CALIBER: 20GA W/TURKEY CHOKE MOSSBERG 500 SYSTEM. 875 CONTOUR ANY 20GA FOREND WILL WORK. FOREND SCREW SIZE/SPACING: 10-32 X 5 CENTERS. SCOPE BASE: DRILLED AND TAPPED FOR A STANDARD T/C 4 HOLE PATTERN.