It depends on whether you have the 22 inch barrel or the 26 inch barrel. If it is the short Bighorn 100 grains of powder is about all you're going to push it. The longer barrel might burn off more powder. I shoot a Wolverine which is a Bighorn stripped down. One conical it shoots very well are Saber Tooth Conicals. I am not sure if they are legal as they are copper jacketed. It also shoots 270 grain Buffalo Ball-ets which are nothing more then a fancy roundball. It does well with them and you get a little more weight then with a roundball.