It's an older Douglas with a 1 in 10 twist, 26 inches long. I am using 72.5 grains of H-4831 SC. FWIW, I have so much leade in the tube that I am going to the 200 grain Accubond. I can seat the 200 grainers .005-.010 off the lands, have a bit over one diameter in the neck, and still function through the magazine. What more could a guy want?