I traded for a gorgeous .458 American, built on an o3a3 springfield... maple fiddleback fajen stock with exotic wood on forend and pistol grip.. beuhler 1 piece base and solid rings, holding a weaver k3 scope... barrel is 24"... I got lots of handloaded ammunition with cast bullets.... shot and salvaged the loaded ammunition... and i'd like to reload now... looking for pet loads, ... i'd like to try the 350 jacketed, 405 jacketed, 380 cast.... what have you???... thanks in advance, jim

the 450 marlin in internally identical, but at lower operating pressures -

that is, for a starting point in loads

in fact, you can "rechamber" to 450 marlin, and use that -- but kind of defeats the purpose of the 2"

I use 450 marlin reloading data (apart from length, I believe that the only other difference is the wider belt that the marlin uses.).
I have had good luck with 350 gr jacketed bullets for bear and bison with this load. Mine is built on a 660 action, and fully scoped, loaded, weighs in at just over 6lbs. Great for packing in the bush (I used it to take my cougar, hunted with the hounds) but you sure feel it when you pull the trigger!!