Flash pan

A Chinese handcannon dated to 1424 with the flash pan adopted from Vietnamese handcannons after the Ming invasion of Vietnam in 1407
A matchlock firearm with its flash pan visible at center as a U-shaped depression

The flash pan or priming pan is a small receptacle for priming powder, found next to the touch hole on muzzle-loading guns. Flash pans are found on gonnes, matchlocks, wheellocks, snaplocks, snaphances, and flintlocks.