The trigger and trigger guard strongly suggest that the gun in question is a double action pistol.
Looking through my "Flaydermans Guide" I don't see where Manhattan or Metropolitan Arms (both of whom made copies of Colts pistols) ever made a Colt copy that was double action.
Colt also never made a double action pistol during the Cap and Ball era.
J. M. Cooper & Co, Philadelphia, Penn did make a double action copy of the Colt open top pistols. The frame, trigger guard and trigger look very much like the photo in "Flayderman's Guide".
During the 1850s-1864 Cooper made a .31 cal pocket pistol which looked very much like a Colt 1849 except for the very large trigger guard and the double action trigger.
From 1864 thru 1869 Cooper & Co made a .36 caliber 5 shot pistol they called the Navy Model. This pistol looks a great deal like the Colt 1862 Pocket Navy (not to be confused with the 1861 Colt Navy with its streamlined round barrel).
They produced about 15,000 of these.
The cylinder did not have the roll engraved cylinder of the Colt and the barrel was marked,
"ADDRESS COOPER FIRE ARMS MFG. CO. FRANKFORD PHILA. PA/PAT JAN 7, 1851 APR 25, 1854 SEPT 4, 1860/SEPT,1, 1863 SEPT.22, 1863 (three lines).
The relief in front of the cylinder is fairly large for elongated bullets and, like the Colt 1860 Army and Colt 1861 Navy it extends thru the area making loading from both sides possible.
The barrel in the photos does not look like the Cooper barrel and it is possible that it was taken from a Colt 1851 Navy.