That is a Philadelphia Arms Co. Fox gun.
See the info here on the A.H. Fox Collectors Association, Inc. web site --
https://www.foxcollectors.com/pre-fox-guns/philadelphia-armsKeep 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.