I agree 9.3- I'd love to have a Marlin with 22" heavy barrel, chambered for the .50 Alaskan - 24" twist for the 550gr. RCBS Bullet.
I've a bit of loading exerience with the .50 Alaskan. My Rolling Block, with a Harry McGowen barrel (St. Anne Ill.) ran 1 1/2 min. of angle at 100 (5 shot groups), then duplicate that at 200yards (5 shot groups), using tang and globe sights. It would do this with either black powder loads or smokeless. I ran it up to 1,950 fps with those 550gr. WW bullets. That would not be a choice load for a Marlin lever gun, but a 1,500fps would be, for North American bears.