In reference to the patent: US 488,366, "Gun-Lock".
You can see the complete patent case file from the U.S. Patent Office at the National Archives at Kansas City. These files normally contain the applicant's oath, original specifications, and communication between the patentee or patentee's attorney and the patent office. The link should take you to the National Archives online catalog page for Patent Case Files with a link part way down the page to email to contact an archivist about these files.
The information in the patent will only get you so far. You at least know that the gun was manufactured after the Grant date of the patent (December 20, 1892), otherwise you would see a "Patent Pending" mark instead of the grant number.
The inventor on that patent is Henri Pieper, who had several other firearm patents and some automobile patents. His company manufactured guns until 1954. The patent mark does not necessarily indicate the model of the firearm, because multiple models may utilize the same invention.
It is possible that another gun manufacturer licensed the patent (paid royalties) to the assignee to use the invention in their own shotgun. I'm not certain what the common practice for marking those would have been at the time.
This is something a vintage firearm expert should be able to help with.