what is the price of a double-barrelled shot-gun made by N.R. Davis & Sons Expert model?

Answer 1

Impossible to answer without seeing the condition, valid proof marks, age, etc. I suggest that you take it to your local gun shop.

Answer 2

I am a Gunsmith/Appraiser, so I'll give you some background on your shotgun along with a value.
In 1929 N. R Davis & Sons firearms merged with Crescent Firearms company to become Crescent Davis Arms Corporation. The company only lasted till 1931 and went belly up and out of business for financial reasons. In late 1931 Savage Arms corporation bought all of the existing,already manufactured parts and equipment from Crescent/Davis and assembled the shotgun pieces into completed double barrel shotguns and sold them under the "Crescent " Firearms Company label.(A division of Savage Arms)
Crescent Firearms is best known for being the maker of "house brand" shotguns for retailers, distributors and mail order companies like Sears and Roebuck, J.C. Penny.Montgomery Wards Etc,etc.
Davis/Crescent, never made any high grade or custom shotguns. Your "Expert" was considered to be an "economy" shotgun at that time and as a result has no collectors value but does have limited value otherwise. Most of these guns were made with hammer forged Damascus steel barrels making them dangerous to shoot with modern shotgun shells and powders. Unless you can find a company that sells black powder loaded shotgun shells like what was made in the 1930's I would reccomend that you DO NOT ATTEMPT TO FIRE THIS SHOTGUN!
A typical value would only be between $60-$100 and only if in excellent condition.
Even today the Crescent