The 1842 Musket could have had Civil War usage. They were typically issued to militia units early in the war and some weren't phased out completely until near the end. I had one at one time that had a soldiers initials and unit carved into stock.
The standard load for them was a "buck and ball" load consisting of a musket ball and three buckshot on top of it. Being a smoothbore it wasn't worth a darn at any kind of range beyond 50 yards, but up close they were devastating.
The 1816 may have also been used in the war as a secondary arm, but I too, think the bolster looks a little off. While the US army did convert some of the earlier obsolete smoothbore muskets into foraging shotguns for troops to use on the frontier, I would bet money it was done after it left government service as the workmanship is just too crude.