Dovetail scope rings

[Vermingone]

On my old Lithgow ( not sure of the model ) there is two grooves cut into the top part of the barrel for the fitment dovetail type mounts for a scope but the right side has not been cut cleanly and therefore doesn't allow me to fit dovetail mounts.
Is there any ideas on how to recut that channel cleanly ? Or is it a gunsmiths job ? Any ideas appreciated Fellas.

[Camel]

I reckon that anyone with a milling machine and the proper cutter should be able to do the job for you. If they can legally do the job is entirely another subject. Depending on how much needs to be taken out and how careful you are, you might be able to do it yourself with a small sharp triangle file.

[bimbo]

depends what you mean by ' not been cut cleanly' but may be something that could be clened up with a small triangle file