It's a franken gun. The lock date is too early for any of the M1847 carbines (cavalry, artillery, and sapper). The M1847s locks are also smaller than M1842 musket locks. If it was a M1847 cavalry carbine it would also have brass furniture.
This gun may be an attempt to make a M1855 Carbine on the cheap, but if that was the intent it was poorly executed.