The 450 is as close to winchester 458 mag 2 1/2 At first I thought it was a 458x2-1/2
I thought the .458 was 2.5" case length.
The .450 Marlin runs 2.550" or so, Overall length.
the .450 Marlin case is 2.100" long, while the .458 Win mag is 2.500" long. The .458 American (or Barnes)is about 2.000" long, and there is a 2.250" long wildcat out there somewhere. The 2.55" length you quote is actually just under the max length the action will handle in length (don't remember the exact number at the moment).
I found a couple nice donor actions yesterday afternoon for the .405 project, but the dealer and I have different view points on the price tag. I did speak with a buddy that would know, and he said to go with a 2" case length; if not a 1.937" case length. He also said to think about a rimmed (or flanged) case, but the .444 case would work pretty well. He's going to give me a handfull of 30-40Krag cases to experiment with. He told me if I wanted to do it in a true 40 caliber that he had a couple barrels that were octagon, and of very premium quality (these barrels are over 28" long and can be easilly cut back to what I want). So now I gotta think about wether or not I want a cast bullet gun or a true .405 (actually .411"). But the .444 case woud probably be an easier start. Now if I happen to do this with a Hi-Wall (Hi-Walls always have a sweet spot in my heart), I might make a bottle necked case off the Sharps case at about 2.125" in length. And I have the perfect candidate setting on the rack in absolute mint condidtion. But alas we're about $125 apart
gary
