There has been some discussion over what guns the modern units use in the game, so I thought I would post who uses what weapons. I'm quite impressed with the variety CA put in, and a lot of it is accurate.
Minie Rifle (Generic Percussion Cap Rifles):
Manufacturer: Europe and the USA
Units:
US Marines (Trapdoor Springfield)
Line Infantry
"Bear" Infantry
Sharpshooters
Yugekitai
Aizu Line Units
Levy Infantry (According to the description, most likely the "Gewehr")
Snider-Enfield:
Manufacturer: Britain
Units:
Royal Marines (They seem to use a breach loading variation)
Imperial Infantry
Republic Infantry
Shogunate Infantry
Khitanei
Chassepot Rifle:
Manufacturer: France
Units:
French Marines
Guard Infantry (Shogun, Imperial, Republic)
Spencer Rifle:
Manufacturer: USA
Units:
Imperial Guard Cavalry
Carbine Cavalry
Tosa Riflemen
Smith and Wesson Revolver:
Manufacturer: USA
Units:
Modern Infantry Officers
Revolver Cavalry
General's Bodyguard