As John and others pointed out, there's no cartouche, probably indicating a state contract other than N.J. as theirs were stamped on the rear left of the barrel. The thing that stood out to me was the lack of the word, "STEEL" on the left rear side of the barrel along with inspectors initials, "F.E.M". I've never seen a Colt without these, (but I haven't seen em all either). Are they there and just don't show in the photos?
Colt was the only contractor to achieve 100% acceptance to the federal gov't on long arms, Alfred Jenks, (marked "Bridesburg" true 1861 models came close with 99.7%). The gov't in February of 1863 decided the Colt had some features that were desirable over the U.S. 1861 riflemusket and made changes accordingly adopting the U.S. 1863 riflemusket, (although very few parts would interchange between the Colt and Springfield). The Colt was the full equal to the 1863 Springfield or the London Armory made P-1853 Enfields ranking it as among the best in the world at the twilight of the muzzle-loading military long arms.
As to what this particular Colt is worth, without a cartouche, "STEEL" on the barrel, inspector/sub inspector initials. "The Horse Soldier" web site, they have an all correct Colt 1861 in nice shape to compare, ($2,700.00). Also, "Lodgewood" sold one recently in lower condition for just under $1,100.00 with a decent bore. Prices now seem to be somewhat inconsistent, I would try to get the one you're looking at for $1,500.00-$1,750.00 if the bore is nice. If it has all the barrel markings and even a faint cartouche, closer to $2,000.00 +. The original Colts are great shooters!
Most Colts in the above condition would sell for above $2,000.00 with cartouche, good shootable bore all correct, etc. One thing that seems to not affect value is a year's difference between the lock date and barrel date. These are considered all original and correct, being assembled in the latter year with some parts from bins from the previous. I do know Colt sold some lower grade 1861's to Schuyler Hartley & Graham during the war rather than tarnish their contract with the federal gov't. These I believe were sold to the state of Conn.
