In the opening battle of the Nez Perce War, fought the length of White Bird Canyon, the regulars advanced and the volunteers were assigned to a flank or maybe to hold horses (accounts vary). The dozen or so volunteers did pretty well ... at surviving--the regulars not nearly as well, losing 34 killed and 4 wounded out of 106. Nez Perce losses were 3 wounded. The volunteers dodged a bullet that day, so to speak.
A couple weeks later at Cottonwood some cavalry regulars got themselves surrounded by the main force of the Nez Perce and 17 volunteers from Mt. Idaho (or perhaps Grangeville), sometimes called the "brave 17," tried to rescue them or at least join in the fight. The brave 17 were also surrounded, their captain was killed, and about four additional volunteers were killed or wounded--could've been much worse. They also reportedly inflicted the first KIA on the Nez Perce when they shot a tribe member described as "elderly." Accounts of all the shooting suggest that the brave 17 must've carried more ammo (and weapons) than the Pataha Rangers had when they mustered. I haven't seen any definitive documents about other volunteer units with Spencers, but suspect most of the volunteers carried similar types of armament. After the war four members of the Mt. Idaho volunteers submitted claims for lost Henry rifles at $50 each.