Im looking for a light cast 30-30 load for 100 or less yard plinking and maybe some jack rabbit hunting. I dont cast my own bullets yet so i will need a bullet that is already manufactured by some company. Im using this in a marlin 336 with ballard rifling. I dont know if the heavier 170 grain bullets would be ok or go with something lighter. Would i need to expand the case mouth to except the larger .310 bullet? Im also stuck on shat powder to use. I dont know if i need a magnum pistol powder or a rifle powder. If possible a rifle powder would be better because it is easiest for me to get. Do i need hard cast or standard? Im also looking for a lower velocity round so gas checks are not an issue. Lastly, how do i create a load that will not lead up the barrel? Anyone help is appreciated im not really sure where to start on this one i mostly work with jacketed bullets. Thanks guys!