Which tool is used to seat the primer onto the nipple of a firearm?

The tool specifically designed for seating the primer onto the nipple of a muzzleloading firearm is the priming tool. This tool is engineered to safely and efficiently insert the primer into place, ensuring a proper ignition when the firearm is fired.

Using a priming tool minimizes the risk of damaging the primer or the firearm itself during the process. It allows the user to apply the necessary pressure and precision needed for an effective seating without the risk of accidental discharge, which can occur if not properly managed.

In contrast, other tools mentioned, like a patch puller or cleaning jag, serve different purposes, such as aiding in the cleaning or maintenance of the firearm, and are not intended for handling primers. The CO2 bullet discharger is related to different types of ammunition tools and does not play a role in the primer seating process for muzzleloaders. Thus, understanding the function and proper use of a priming tool is essential for safe and effective muzzleloading practices.