That is a Philadelphia Arms Co. Fox gun.

[Linked Image from i.imgur.com]

See the info here on the A.H. Fox Collectors Association, Inc. web site --

https://www.foxcollectors.com/pre-fox-guns/philadelphia-arms

Keep in mind that at the time of the Philadelphia Arms Co. Fox doubles the longer shells offered by our manufacturers didn't carry heavier loads than could be had in 2 3/4-inch shells. They had more/better wadding which many gun cranks considered an advantage. My gun the C-Grade pictured on the AHFCA site is chambered for 3-inch shells.

Could I have some more info on 1612? Barrel length? Grip style? I have been keeping track of observed Philadelphia Arms Co. guns. I've recorded 93 guns, or parts thereof, with extractors from serial number 51 to 1846. A single ejector gun with a serial number in the 26xx range has been observed.