Blunderbuss is like a shotgun. Instead of having a single ball, it was loaded with scrap metal, the flared end sending the metal in all directions. It was popular on ships as it could be used to stop enemy sailors and marines from boarding your ship. Canons were sometimes loaded with scrap metal too for the same effect but more violent obviously. It was called grapeshot. Napoleon famously used it against rioters in Paris.
Your base weapon is a flintlock which is missing the frizzen (also called a steel), as is the earlier pirate pistol which also flares though this may be a percussion cap pistol. The second generation pirate pistol has the frizzen, though the whole mechanism is on the wrong side. The latest pirate pistol seems to be flintlock that is missing the frizzen - it's the ugliest of the three as well.
So far as I'm aware, the civil war long weapons are mostly percussion cap weapons. The exception being the lever action rifles. I think these are meant to be winchester rifles but they didn't exist during the civil war but the earlier Henry rifle did. It's only appropriate to use these for Union cavalry though.
Typically the northern cavalry used short versions of the infantry rifle while the southern cavalry relied on revolvers. Confederate cavalrymen carried two pistols generally and some units carried up to four. Normal infantry rifles were also used.
If you haven't seen them yet, playmoebius does a matchlock musket which might be of use though it is missing the match. It comes in brown or black.
http://www.playmoebius.com/weaponry/classic-weaponry/50-mosquet-s-xvi-brown.html