80-85 T7ff, 300gn XTP, mmp short black sabot. 1 1/2" groups. with a scope and shooting off of bags.
On the breech plug use thread tape and permatex High temp antisieze 1600 degrees (auto store) or better yet some nickle silver 2000.
Break it loose 1/3 turn after 5 shots and retighten or You will seize it. If you don't you'll be putting the whole thing in a vise to get the plug out.

Good luck, they shoot great and will shoot about anyting bullet wise from a .430 with green mmp's to 460 conicals.