Looks like it is a Model 1876 Carbine model that has been modified. It has a carbine barrel band and a shorter than full length magazine tube. The saddle ring hole on the left side of the receiver can also be seen, kinda confirming it started out as a carbine before being modified. All 1876 Carbines and Muskets had full length wood forends with a distinct metal forend tip. True 1876 carbines are pretty rare....gotta be very wary of mods and fakes.
1876's came in three models.....first model, second model and third model. These are typically differentiated by the top dust cover type and by serial number range. 1st models SN range are approximately 1-3000. 2nd Model 3000-25000. 3rd Model 25000 - end
Winchester did not offer the 1876 in the 45-60 chambering until 1879, so the serial number on this gun should be above SN 7968 and will be either a 2nd or 3rd model.
You should be able to see the Model # designation engraved on the upper tang behind the trigger and the serial number will be on the lower tang under the lever.
Those would be a great help in determining value.
The barrel should be 22" long as a carbine model (muskets had 32" barrels) and the barrel should be marked with the Winchester address and the Kings patent date.
Serial number did not designate between rifles, carbines or muskets.
