Huffy.
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.
They were made for the Shapleigh hardware store chain roughly 1920-s-early 1940s.
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.
Made for Shapleigh Hardware by Harrington & Richardson, before WW2. Value under $100.
Sold by Shapleigh Hardware in Missouri. Probably made by Stevens, although other companies also made Bridge Gun Co guns.
The address of the Shapleigh Community Library is: 607 Shapleigh Corner Road, Shapleigh, 04076 0097
Mississippi Arms Co was a trade name used by the H.D. Folsom Arms Company on firearms made for the Shapleigh Hardware Company of St. Louis, MO.
There was no Central Arms Company. This is a trade name used on guns sold by Shapleigh hardware. Your gun was likely made by Stevens.
Known tradename used by Shapleigh Hardware. The guns were made by several different manufacturers, although your double is probably a Crescent. 1900-1930.
Mississippi Valley Arms Company: Trade name by the H. & D. Folsom Arms Company on firearms made for the Shapleigh Hardware Company of St. Louis, Missouri. Folsom was a wholesale/retail company and the guns were manufactured by their subsidiary company, Crescent Firearms of Meriden, CT, or by various Belgian makers.
Some Enders Royal Service shotguns are Crescent Model 60's marked with Shapleigh Hardware's trade name, but some were made by other manufacturers.
King Nitro was a trade name used by Shapleigh Hardware of St Louise on guns made by Crescent Firearms and J. Stevens Arms.