Thanks Ivan for the addicional informationivan salis said:you bet they used shotguns --esp confederate calvary troops --they used sawed off double barrels at up close and personal range with buckshot from horse back to clear off union nfantry as they tried to mob em -- they worked very well for that .
a 12 gauge long barreled shotgun could use buckshot (if the action was to be up close) or they could use a 69 cal round ball or a slug for more range ( buckshot was normally used if sawed off since it was a close quarters only type weapon )