A year or so ago, a very good client of ours purchased from a used gun dealer this .476 double rifle, it is a Gold Name model rifle made in the early 1900's. Having received it he then had problems getting it to shoot and so sent it across the Atlantic for us to have a look at.
The rifle had, unfortunately, been shot at some point with monolithic solid bullets which had pushed the rifling to the outside of the barrels rather than being on the inside. Worse still there was a hairline crack in the centre of the barrel, barely noticeable unless you look carefully, rendering them as scrap.
Whilst hugely disappointing for the client I was very pleased that he immediately thought of sending us the rifle to check, rather than load and try to get the rifle to shoot himself. The barrels were totally unsafe and the crack could at any point have opened up and potentially caused injury.
I have come across quite a lot of old rifles which have been shot with the wrong ammunition, and whilst I will not say this is a common problem, it is not uncommon either. When you are buying a double rifle ( or shotgun in fact) the barrels are the most expensive item to replace and it is worth thinking a vintage gun is only as good as its barrels. Spend the time to check them or have someone check them for you. It is possible in the case of the rifle to see the rifling on the outside if it has been raised by the wrong solid use, hold the barrels to the light and look up the outsides and you can see the feint twist of the rifling. This is perhaps easier said than done but worth remembering to check or ask someone to check for you! The penalty is a bill for in excess of $20,000 for new ones!