What is the term used for the mechanism that holds the ignition source in place in caplock firearms?

The term used for the mechanism that holds the ignition source in place in caplock firearms is the nipple. The nipple is a small metal fitting that is secured to the firearm and allows for the placement of a percussion cap. When the trigger is pulled, the hammer strikes the cap, igniting the powder charge and firing the projectile. This mechanism is essential for the functioning of caplock firearms, as it effectively connects the ignition source to the firing channel.

In the context of the other options, the patch box is a compartment in the stock of a muzzleloader where patches and other accessories can be stored, but it does not relate to the ignition mechanism. The ramrod is used to push the bullet and powder down the barrel, serving an entirely different function related to loading the firearm. The lock plate is the part of the firearm that houses the firing mechanism, including the hammer and the spring, but it does not specifically refer to the component that holds the ignition source like the nipple does.