Which preposition to use with primings

of Occurrences 14%

"There is more in this than an ordinary assault," I heard the sergeant mutter, as he looked to the priming of his musket.

in Occurrences 3%

The matchlock was fired by a match fixed by a kind of tongs in the serpentine or cock, which, by pulling the trigger, was brought down with great quickness upon the priming in the pan, over which there was a sliding cover, which was drawn back by the hand just at the time of firing.

Which preposition to use with  primings