Im considering having C Sharps build me a rifle in 38-55 ( either a Hepburn or a high wall havent decided yet). I want to shoot bullets around 300-350 grns for shillouettes ( swingers) we normally shoot out to 500 yds. Id like to know what twist barrel you guys are using? C Sharps is now offering Mc Gowen barrels also. I also thought about 38-56 but dont want to get into the case forming. Im planning on a 30" barrel and finished rifle wieght of 9 1/2-10 1/2 lbs. upgraded walunt stock and forearm. Ladder rear mount and front spirit globe, set trigger and steel butt plate. But Im not sure on twist rate for these bullets or thier length. Thanks for the information and help.