eldeguello, I should have said .458 vs .457 on the groove size but groove dimension is how CF barrels are measured. Land size on such a barrel would typically be .450-.451. A .457/8 cast boolet would be terribly difficult to load in a CF .458 barrel.

Size them for the lands and you would have a slip-fit boolet - easy to load and probably quite accurate with moderate charges.

and a ps: a call to Krieger/Criterion might locate JUST the right barrel for such a project.