The 8th Texas calvary (Terry's Texas Rangers) threw away their carbines and sabers and carried 2 pistols and 2 side by side shotguns. 6+6+2+2 = superior CW firepower!
In the entire war, there were only 2 instances in which mounted calvary caused infantry to turn and run. The 8th caused that event both times.
With fearsome weapons. The short shotgun loaded with 00 buck was a short-range weapon but if you were on the receiving end it meant, at the very least, some serious maiming. A mounted man, with a shotgun, most severiously meant that your best course of action was to run like you've never run before.