Anyone able to offer comments on this?
The lock plate is dated 1863 behind the hammer. 1863 is also on the top of the barrel. Several govt inspection stamps as well as US in various places. It looks like an white 1863 Springfield but "Norfolk" and WW Welch. I'm guessing the designation is that of a station or unit assignment. There is a numeral "7" on the top of the butt plate.
One search result with this info.
HOWDY, I WANT YOU TO HOLD HISTORY IN YOUR HANDS. THIS IS A VERY INTERESTING PIECE WHICH COULD HAVE SURVIVED THE CIVIL WAR. IT IS A 1861 MODEL SPRINGFIELD DATED 1863 AND MARKED U.S. NORFOLK. THIS IS CALLED A CONTRACT SPRINGFIELD. ACCORDING TO MY RESEARCH IT WAS MADE BY W. W. WELCH IN NORFOLK CONNETICUT IN 1863 AND WAS ONE OF 8000 RIFLES MADE THAT YEAR. ONE OF A TOTAL 17,000 MADE BETWEEN 1861 AND 1863.