RCMP policy requires a barrel breech/cylinder weld when a revolver is deactivated. Apart from that requirement, there is no specification requiring obtrusive external welds.
If a gunsmith doesn't have the knowledge, equipment and skill to do unobtrusive work, then he is a hack and shouldn't be doing what he can't do well.
If a gunsmith doesn't have the knowledge, equipment and skill to do unobtrusive work, then he is a hack and shouldn't be doing what he can't do well.