I suspect if you get a 400 grain pill moving 2,100 fps out of the 405 Winny, you'll be pushing something in the neighborhood of 70,000+ psi pressure. Don't try to make the cartridge something it isn't.

If you do use those type of loadings very long, you'll likely shoot your rifle loose or have it come apart in your hands. Either way, its not a good idea.

The Ruger No.l is a very strong action, but if you are going to try to make the 405 a 400/450, why not just rechamber to that round and hold the pressures down?