Noun
caplock (plural caplocks)
A firearm that is discharged by means of a percussion cap.
Antique firearm display in the main entrance to the Cody Firearms Museum Percussion cap further Percussion caps ( caplock mechanisms ), coming into wide service in the 19th century, were a dramatic improvement over flintlocks. Source: Internet
These were caplocks or "cap and ball" revolvers, because the caplock method of priming was the first to be compact enough to make a practical revolver feasible. Source: Internet