I found some more interesting items in the newspapers of the day.
It seems a common habit to load pistols with two balls. Many items to that effect, here are two:
"The South Carolina Gazette
June 21, 1742
Charleston, South Carolina
This Day a melancholly Accident happened in this Place”¦. shot herself with a Pistol, loaded with a Brace of Balls, through the Body; and expired in an Hour or two after,"
"The Pennsylvania Gazette
February 12, 1783
The Negroe having a pistol in his hand, discharged it at the subscriber, and the two balls that were in the pistol, hit the leather jacket he had on, but did not enter his body, though he was very much hurt, "
The military used cartridges, this item for mounted troops:
"The Pennsylvania Gazette
April 24, 1793
An ACT for the regulation of the Militia of the Commonwealth of Pennsylvania. ”¦. a pair of boots and spurs, a pair of pistols, a sabre, and cartouch box to contain twelve cartridges for pistols;"
And now I'll feel perfectly HC when I go after squirrels with my pistol loaded with shot:
"The Pennsylvania Gazette
March 28, 1751
”¦.taking his Pistols with him, he went down, and opened his Door, and seeing three Persons, discharged one of the Pistols, which was loaded with Pidgeon Shot, amongst them, and presently the second,”¦."
Spence