Thanks to all for their replies. Small Bore, does the 12C in a diamond indicate the chamber length as well as the diameter? When I first bought the gun I was told it was 3", but I measured it yesterday and they are definately 2 3/4" so they must have been lengthened. What type of marks should show on a gun with 2 3/4" chambers in 1904? I live in northern Canada and there aren't any gunsmiths around here. I've called all within a days drive and none have wall thickness or bore diameter gauges. I'll have to buy those tools. Assuming it passed reproof and had good wall thickness what would a gun like this go for at auction in Great Britain? I haven't shot it yet but I was hoping to shoot 1 1/4 oz TM, 2 3/4" handloads at <8000 psi for waterfowl. Sorry for all the questions. I appreciate your sharing your expertise.