guy brings up a good point. With pre 64's the entire actions were heat treated,so there may be some warping. They were set up to work with the factory tubes but when changing barrels sometimes only one lug will bear so they have to be ground for full lug contact, and other smithing tricks they use putting barrels on.
I've run into this when dropping a new barrel onto not only magnum but standard actions as well. Problem is if you do this your old original barrel might not fit anymore so be prepaid for that possibility.
Im commenting not as a smith but as a customer who has had to pay for the work.
None of this would stop me from using an action though LOL!
