A.D. 1866 really wasn't so long ago. Even a Boomer might have heard Grandpa tell stories of the old-timers he knew, guys who were in their prime when White America hadn't quite finished stealing the Redskin West. If he were poor or ludditical, that same pioneer might have lived out his life with a cap and ball rifle, maybe the Model 1861 Springfield he carried home from the War for Southern Autonomy.
But the winds of change were blowing. A few repeaters were on the market in 1866.
That was the year when Washington decided to see if its troopers could swipe the Powder River Country from Red Cloud and his Sioux, Cheyenne, and Arapaho pardners. Turns out they couldn't, though not for lack of trying -- trying in the sense of, say, the Keystone Kops trying to take down a large Mexican drug cartel.
Late in July Lieutenant George Templeton led his motley detachment of 29 men, three women and a child out of Fort Reno. Destination: the site the still-unbuilt Fort Phil Kearney, 60 miles northwest along the Bozeman Trail. Among his crew were a civilian named Captain Marr, lately of the Missouri Volunteers, and Army Chaplain David White.
About half way, at Crazy Woman Creek, the rightful owners rose from the their hidden positions and charged the little batch of invaders who were mostly armed with those '61 Springfield's. In the end, all was well, but just by a hair and with a little help from advanced technology. Let Dee Brown make the points:
In the first attack, "Captain Marr, who had a Henry rifle, a sixteen-shooter, used it with wholesome effect on the running Indians, and stopped two of them permanently."
The Sioux withdrew to regroup and charged again. This time they wounded Chaplain White slightly ("more angered than injured"). He mounted a little counter attack of his own and returned to the his lines shouting. "Ravine clear down as far as the creek."
"All seven charges in his pepperbox had gone off at once, killing one Indian and frightening the others into flight."
"Powder River Country" is a loose descriptor, but it's not too far wrong to think of it as most of northeast Wyoming from the Big Horns almost to the Black Hills.
Mostly from "The Fetterman Massacre" by Dee Brown, 1962, ISBN 0-8032-5730-9. Chapter IV.