A .10" is plenty. This confirmed by Cliff LaBounty who did three rebores for me as well as Ruger who delivered my factory Ruger RS Whelen at .560". Balance can likely be maintained via punching a few holes in the butt. I do like my rifles light too.
Ok, glad it will work. The Kimber's balance isn't great in smaller calibers....it will only be made worse by removing metal. Not sure how to punch a few holes in the butt of a Montana.
