"Store brand" guns usually don't have much value. Maybe 100 USD.
Probably Crescent. They made shotguns known as "hardware store" guns for many businesses, marking them with the name of the store- such as Shapleigh Hardware.
i would like to know this myself i hacve one
Some models of Diamond Arms were made by the Crescent Fire Arms Company for the Shapleigh Hardware Company of St, Louis, Mo. between 1982 and about 1922.
S.H.C. stood for Shapleigh Hardware Company. The shotgun was more than likely made by either a Belgium company or Cresent Fire Arms Com.. It was very common in the late 1800's and early 1900's for arms companies to stamp the hardware stores "logo" on a shotgun or .22 for a fee.
Shapleigh Hardware Company. Would depend on model and condition, but these are fairly low dolalr guns. In working order, about $125
Shapleigh Hardware Company was a large St. Louis wholesale hardware distributor that existed from the 1880's up until the 1950's. They sold large numbers of guns with both name brands and their own "private label." Both domestic and imports. The Shapleigh family was prominent in St. Louis business and charitble circles, and served on many boards of directors. There are still a few descendants active in St. Louis.
You have already identified it as a Shapleigh's King Nitro. Shapleigh Hardware was in St Louis Missouri from the mid 19th century until the middle of the 20th. Their King Nitro guns were manufactured by W.H. Davenport and later by Stevens/Savage.
Central Arms Company was a trade name used by the W.H. Davenport Firearms Company on shotguns made for the Shapleigh Hardware Company of St. Louis. MO.
BRIDGE GUN COMPANY Tradename used by Shapleigh Hardware of St. Louis, Missouri on shotguns made by Crescent Fire Arms Company c. 1893-1930.
Your shotgun was actually manufactured by the Crescent Firearms Co. of Conn. They were prolific producers of what are called "Hardware Guns". Crescent produced shotguns for any company or distributor with their name on it, if they paid for the cost of the stamp.They produced under several hundred different names. A Googe search will provide more information.
Some Enders Royal Service shotguns are Crescent Model 60's marked with Shapleigh Hardware's trade name, but some were made by other manufacturers.
Known tradename used by Shapleigh Hardware. The guns were made by several different manufacturers, although your double is probably a Crescent. 1900-1930.