NEW PRODUCTION THOMPSON CENTER BARRELS MADE IN NH. PLATFORM: THOMPSON CENTER Encore PROHUNTER. CALIBER: 300 WIN MAG. RATE OF TWIST: 1 IN 10. 810 HEAVY CONTOUR ANY pistol FOREND WILL WORK FINE. FOREND SCREW SIZE/SPACING: 8-40 / 5 Centers. THREADS: Yes 5/8-24 THREAD. SCOPE BASE: DRILLED AND TAPPED ONLY FOR A STANDARD T/C 4 HOLE BASE.