When forcing cone lengthening became fashionable here about 1988 or there abouts it was very common practice for gunshops and gunsmiths to advertise this work and to carry it out often on a while you wait process.
Indeed GMK the British Beretta importers used to have their resident gunsmith Gordon Swatton doing it at Game Fairs and competitions such as the British & English Opens.
It did not contravene Proof House regulations, maybe times have changed and Birmingham have bullied their way into the scenario.
It is typically a cock up, because Proof Law clearly says that if you alter a proved barrel in any way it renders it out of proof. That is why you have to have it reproved if you multichoke a fixed barrel.
