It is indeed one heck of a gun. It appears to be a barn find, as there seems to be water damage and a bent tang. It is untouched however and that says a lot. Price to be determined, as you said, Frank.
Oddly, the wood box, J.P. Beck, at another auction apprarently did not meet the number, (range much lower than this one), so it didn't sell. They are now taking offers on it. With that one in mind, it will indeed be instructive to see what this Armstong gavels down for.
Dick