In muzzleloading, what is commonly used to denote that a firearm is ready to fire?

In muzzleloading firearms, the state of readiness to fire is best indicated by the presence of a properly seated percussion cap. The percussion cap is a small metal cap that contains a shock-sensitive explosive compound. When the hammer of the firearm strikes the cap, it ignites the powder charge within the barrel, facilitating the firing process.

A properly seated percussion cap ensures that it is securely attached to the nipple of the firearm, which allows for reliable ignition when the firearm is prepared for use. This is crucial because if the cap is not seated correctly, it may not fire when the hammer strikes, leading to a misfire or failure to discharge.

The other options, while important components of muzzleloading operation, do not directly indicate that the firearm is ready to fire. For instance, a secured ramrod is necessary for ensuring that the projectile is properly seated in the barrel, but it does not relate to the ignition mechanism. An adjusted patch box pertains to the storage of patches and balls, and an engaged hammer indicates that the firearm is cocked but does not confirm the readiness to fire without the percussion cap in place.