I want to know what twist a barrel in caliber 450 NE shall have? I know that the 458WM have 1:14" and a 45-70 have 1:18" It�s good to choose a barrel with 1:18 twist?

Who makes brass wich is strong for this caliber?

It�s possible to get 2200 f/s from a 470 NE without to get high pressure?

wich one of this two calibers is the best to go with to build a rifle on a Ruger no1?

The simple way is to have a 458 rechambered to 450 NE. I had my 458 rechambered and rebored to 470 NE by Bowen (Labounty did the reboring). You can easily get 2200 FPS out of the 470, but NOT in a double rifle.

For a Ruger #1, it is possible to get 2200 fps in either cartridge. Easier to get the 470 nitro to do this, however, without lots of tinkering with powders, drop funnels, etc. due to the limited case capacity of the 458 Win.

I have both and have loaded both.

Ditto on not trying for higher velocities in a double rifle, which the Ruger is not.

Bell brass seems to be OK.