Black Hills 125 gr JHPs! 625 ft/lbs of energy at the muzzle. Buffalo Bore makes some hunting rounds that are even hotter but for HD, the Black Hills will do. You cannot shoot a better self defense round ( in any caliber) than the Black Hills 125gr JHP. The GP-100 shoots'em like a champ, all day long. Any good self defense load in .357 magnum will serve you well, from the old school 158gr wadcutters to the Glazer Silver Dot 110gr frangable rounds. As far as range shooting, I shoot the cheapest target loads I can find at Wally World. I also like to shoot 38 special loads, especially with a new shooter. The .357 will get your GP-100 so hot you could iron your clothes with it. 38 specials don't heat up the gun so bad. 38sp +P? I don't mess with them. I like the Hogue mono grips. It makes shooting hot loads easy on the hands. I shoot both hands, strong hand and weak hand with no problems.