I had a rifle like yours, it shot well with jacketed bullets but I never could get it to shoot well with cast, partly because of its large .431" bore. The Lee loader should make serviceable ammo, I've dabbled with a couple of the Lee kits and they work, but are tedious to use for any quantity. The most common available Jacketed bullet is the Hornady 240 gr. HP XTP. It is not recommended by Hornady as a deer bullet, because it tends to open a bit too quickly and penetration may suffer. Lots of deer have been killed with them though, and if you place that bullet in the ribs, they'll work OK. In any case, avoid the lightweight bullets, they open faster yet and penetrate less. I'd suggest you look for a jacketed 240 soft point, not hollow point. But they are very scarce in the stores. as for going heavier, I don't think the slow twist rate on that rifle is compatible with bullets much over 240 grains. Good luck!