The VP & Eagle are proof marks. The picture is that of an M1861 but they would be similar if not the same.
View attachment 128560
The U references up so the barrel bands are placed on the weapon correctly.
US on the butt plate is standard, the three spring fastened bands are typical of the M1863 as well as the Special Model 1861. What does it say on the lockplate? Pics are advisable.