I've been playing with mine a little lately. I haven't noticed much change in accuracy with different powder loads. I've used any where from 100grains to 150grains and bullets from 240grains to upper 300's. slap a scope on it to work up a good accurate load andthen take it off and get it where you want with open sights. A lot of people will bad mouth the X-150 but I've shot 5 or 6 of them and killed game with 3 different guns, they shoot well for me.