You have a best quality Alex Henry dropping block miniature express rifle. Condition looks good, not excellent. The takedown "screw" is unusual, but appears to be original. The "cranked" lockplate is only found on a few best quality actions. A cased example in excellent condition having nearly all of its blue and case colors, even on the heel and toe plates, recently sold for $7500 at auction. and was probably a bargain at that. Theese are wonderful small deer rifles weighing in at less than 5#. I would suggest going the auction route to maximize return.
All the best, Mal