what is the math for barrel od in chamber area?

[22to45]

Gentlemen:
I am thinking re-using a mauser small ring 6.5 barrel in a larger action and want to try a 6.5 rem mag, or even a 264 win mag if there is enough metal in the barrel to put that large of a chamber in it. I know a fellow who regulary cut 6.5/06 chambers in small ring mausers, I am just wondering what the limits are.
Thanks
Allen

 

[gunpro]

I think he was pushing the limit on the chamber already. Kind of a rule of thumb especially on the milsurps is not to exceed the chamber pressures of the round for which it was designed. I don't have a reference beside me here but a quick think would have either magnum exceeding the original calibre. not to mention that the bolt face has to be altered as well. Buy a Stevens with a magnum bolt face if you want to play. just my 2 cents others may disagree.