Hello friends I have an action cz 550 mágnum was a cz 550 300win mag want to make a custom that caliber could call may be something in cal. 375 or 416? Or that I recommend greetings.

the 550 magnum action was made, for awhile, in 300win,.. that is to say, not the medium.

it is the same action of the 375, 416, and nore 450/505/500 stuff..

You can make nearly anything from it

Thank you for responding to think of the 375 Ruger will make a custom action with this

IMO it would be a little of a waste to put the .375 Ruger on that action. The Ruger was designed for standard length actions of the .30-06 size whereas the CZ is so much bigger than what is needed for the Ruger.

I agree and even the .375H&H is too small for that action, a very good one, IMHO. I had a Brno 602 in .375H&H for awhile, but, got rid of it and went to P-64s in that chambering, which are ideal.

I would go with a .404 Jeffrey or .416 Rigby or perhaps a .458Lott, if you want a heavy rifle and a .375RUM if you want a .375 bore size...this, btw, is what a friend uses guiding Polar Bear tours in the Canadian arctic and this is a sound use for that action.

Thank you for your comments the sizes are pleasing to me are the 375H&H 458 Lott 416Rigby

Any of those 3 are much more suited for your action.