by Timothy P. Banse
Winchester's Triple Se7en 209 muzzleloading primer is perhaps the most significant advance in inline muzzleloading ignition since the advent of the 209 primer. It's easy to spot at a glance, with its black primer face, so there's no confusing it with a conventional 209 primer.
With the arrival of Triple Se7en granular powder (circa 2002) came the promise of better than black powder velocities. Triple 7 pellets followed. From day one Hodgdon recommended lighting off Triple Se7en powder charges with 209 primers. but there was a problem: Nasty, hard, slag-like fouling crud (the notorious crud ring) that formed in front of some, but not all, 209-fired breechplugs.
In search of a solution, Olin-Winchester diligently researched and developed a new primer compound from scratch, with the goal of eliminating, or at least dramatically reducing, the crud ring from Triple Se7en and Pyrodex. Ultimately, they created a clean, reliable ignition.
Winchester Triple Se7en Primers are specifically designed for Muzzleloading and are milder than typical 209 Shotshell Primers. The good news is that milder primers do not force the powder charge forward. This helps maintain consistent velocities and minimize formation of crud rings. More specifically, it's a fact that Winchester T7 primers significantly reduce fouling build-up in muzzleloaders and reduce carbon build-up inside breech plugs.
Early on we mentioned how to ID a Triple Se7en primer with its black face. Besides the visual cue, its outside dimensions measure virtually identical to standard W209 primers, so it can be used in place of a standard Winchester 209 in any muzzleloader designed for 209 primers.
Finally, a caveat: Do not under any circumstance use these primers with smokeless propellants.