15/1 means a .685 bore 9" from the breech, according to the chart in W W Greener's "The Gun and its Development". Since 12 is .729, that is quite a tight bore. You sure its a "15" and not a "13"? 13 would be more usual.

At any rate, as friend SKB points out - find the bore sizes and wall thicknesses now. See how much the thing has been polished/honed. I would expect a Midland gun to run in the lower end of SKB's price range.

Good luck with your find.

Regards

GKT

Texas Declaration of Independence 1836 -The Indictment against the dictatorship, Para.16:"It has demanded us to deliver up our arms, which are essential to our defence, the rightful property of freemen, and formidable only to tyrannical governments."