Winchester Triple Seven Primers 209 Muzzleloading are intended specifically for muzzleloading and are gentler than standard 209 Shotshell Primers. Milder primers do not drive the powder charge forward, which helps to keep velocities steady and crud rings to a minimum.

These primers have been carefully tested for consistency and sensitivity at temperatures and circumstances much beyond the standard operating range. Winchester offers improved sensitivity for more positive fire in all guns, consistent size and quality, and stability in temperature and humidity extremes. These primers are not intended for use in shotshells; they are only for muzzleloading guns.