I have had good luck with a few loads. One being 40-41 grains of Reloder 7 with a Lee 340 grain cast bullet (unsized). The recoil gets to be a bit much if you go over the 41 grains of powder. The Hornady 300 grain HP using the same powder charge works very well also. We have also had good accuracy with LeverEvolutions as well. This tends to make me think the gun is not picky, so I would stick with the powder and bullets you have. There are a lot of folks out there using the Lee bullet you have and 4198 with good results, so you probably already have a winner combination without investing any more cash.