Hi Bushveld, I have just done some barrels for Mike Harrel his barrels are going back via the cheshire gun room although I dont know the costs perhaps mike can tell you, I am trying to talk my wife into a move to canada but she is having none of it at the moment!! I do use nitric acid and I am still trying to improve my lustre, it certainly affects the final finish so does the rusting time, my process only takes 3 days once the barrels have been degreased, my grandfather was better at this than I am so I have a bit more to do yet to get to his standard, when he was alive he did all the barrels for Purdey, Boss, Holland and Holland etc all the top makers, who does your finishing over here?