I recently inherited an Ithaca featherweight semi-auto 12 ga. from my father in law.This is one of his favorite shotguns and as his son in law I am happy to be receiving it. However as with most older type shotguns it has a fixed mod. choke. I was thinking of having the barrel modified so I would be able to use screw in type chokes. Has anybody had this done? What are your thoughts on doing this to an older shotgun?