If you want hypothetical situations, there are a few thanks to Fort Union in New Mexico. One such situation would be an armed response to the peons joining the army in 1861, perhaps an armed band trying to bring them back to the farms while the army tries to keep them (which did not happen, because the patrons went with litigation to challenge the enlistment of their property, and the military responded by suspending the writ of habeas corpus in the territory). Or perhaps the feuding between Fort Union and Loma Parda, that got bad enough that a small detachment looking for AWOL drunks was arrested by the mayor, and the army responded by sending in a larger detachment (but cooler heads prevailed, and nothing came of it outside of a military apology and better guards posted at the fort). The army was called out on occasion to chase down gunslingers and armed gangs. During the rise of populism and populist terrorism in the 1880s and 1890s, the army joined in the hunt for the Gorras Blancas. The army was also called out on occasion to chase Anglo settlers off of Indian land. These hypothetical situations could work anywhere from 1851 to 1891, giving a very long range of possible US cavalry weapons from dragoon pistols and M1841 rifles to the trapdoor Springfields. The army had gatling guns and mountain howitzers at Fort Stanton, which would make for exciting skirmishes. Particularly bold thieves could try to target the Fort Union warehouses, since most soldiers were usually out on detached duty (chasing the outlaws and Indians, along with other purposes) and many of the people remaining at the quartermaster areas were civilian contractors.