Hello:

Does anyone have any comments on these cartridges re: 'shootability' and availability of dies and brass?

Cheers!

M Batten

I used to own a very nice Alex Henry double rifle in 450-400. I have taken black bears with it. Shoots very nice with 41 caliber cast pistol bullets. I'd think that the 450 3 1/4 would be quite a bit more powerful.

As Mike says, the 450 is far more powerful and also has an advantage over the 450/400 2-3/8" version in the component availability department.
Any 450 Nitro Express brass can be used and dies are available right off the shelf. Plus there are about a jillion bullet molds and store bought bullets out there to try.