its liekly from the 1850's to 1900 time frame. most cheaper shotguns were imported by american resellers. they would buy them from mass produced sources in various european countries, mainly england, and they would come over without any maker marks and the buyer would put their mark on them and resell them. proof marks and any identifiers are normally found under the barrels near the locking mechanism.
pics would help greatly of any markings and overall of the gun itself.
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"Gun control: The theory that a woman found dead in an alley, raped and strangled with her panty hose, is somehow morally superior to a woman explaining to police how her attacker got that fatal bullet wound." L. Neil Smith
The problem with being stupid is you cannot simply decide to stop doing dumb things...