Spencers could have some downsides, ie: limited ammo and makes a lot of smoke when fired:
The Spencer showed itself to be very reliable under combat conditions, with a sustainable rate-of-fire in excess of 20 rounds per minute. Compared to standard muzzle-loaders, with a rate of fire of 2–3 rounds per minute, this represented a significant tactical advantage.[10] However, effective tactics had yet to be developed to take advantage of the higher rate of fire. Similarly, the supply chain was not equipped to carry the extra ammunition. Detractors would also complain that the amount of smoke produced was such that it was hard to see the enemy.[11]http://en.wikipedia.org/wiki/Spencer_repeating_rifleNot sure what the devs will choose as a comparable weapon but the southern cavalry may have used pistols quite a bit afaik:
Pistols, which Southern cavalrymen generally preferred over sabers, were usually six-shot revolvers, in .36- or .44-caliber, from Colt or Remington. They were useful only in close fighting since they had little accuracy. It was common for cavalrymen to carry two revolvers, for extra firepower, and John Mosby's troopers often carried four each.
http://en.wikipedia.org/wiki/Cavalry_in_the_American_Civil_War
