Could anybody help me out with case dimentions, and loading source for the .450 American.
I believe Marlin had a rifle chambered for it.
Any help would be much appreciated.
Best Regards

Old Ford

What you are probably thinking of is the .450 Marlin. It is a belted cse with the belt wider than standard and a 2.1" case length. It was intended to be an alternative for people wantingclass 3 .45-70 load equivalent, but not wanting to reload.

The .458 American, AKA .458x2", was developed by Barnes for bolt action rfles, and basically is a reduced capacity .458 Win. Mwg. The intent was somewhat reduced performance more applicable to North American game than the .458 Magnum. It is a wildcat. I am not aware of any production rifle ever being chambered for it. It is nothing more than the .458 Magnum reduced to a nominal case length of 2.00". Data can be found in Barnes "Cartridges of the World".

The 450 Marlin is a great cartridge, but, I use a 45-70. The American as posted is a wildcat and I have never heard of it chambered in a "factory" rifle.