The problem with primers: sometimes it is the simplest things, such as a little spark, that turn out to be not that simple at all.
When blackpowder substitutes came along, the shooting community found big advantages over cantankerous blackpowder with one exception--ignition. Black powder just begs to burn, but substitute propellants are a little tricky. Their chemical composition is more difficult to burn, especially when pressed into pellets. Hodgdon even went to the trouble of adding a few grains of good old black powder to the base of Pyrodex pellets and a hole through the middle in an effort to jumpstart the process. When Triple Seven exploded on the scene, 209 primers quickly became the preferred ignition method since they have a higher ignition temperature and engineers did not want to add a blackpowder accelerant to the sulfur-free Triple Seven formula.
The 209 primer's powerful jet of super-hot gases, while great for ignition, caused its own set of problems. In the few nanoseconds before ignition, the gas would actually push the pellets and bullet up the bore. When the pellets did finally burn, the combination of this extra space and primer and propellant fouling would create a nasty crud ring where the pellets and sabot/bullet met. Breech-plug design could limit or exacerbate the problem, as could the rifle's action type. The crud ring was nastier than run-of-the-mill fouling, almost immune to between-shots swabbing and caused consistency issues. The crud was a real accuracy killer.
Shooters soon started experimenting with different primers and found reduced-power Remmington .410 primers not only helped the crud ring in many cases, but also reduced fouling. The trade off--there is always a catch--was ignition reliability sometimes suffered. Winchester went to work on the problem first and soon introduced a reduced-power primer that reliably ignited both Triple Seven loose and pelletized propellant. The primer works well, and I shoot both propellants by the case without issue.
Federal recently entered the fray with its Fusion 209 inline muz-zleloading primer. So far, it has done well in my testing. Your rifle/propellant/bullet combination will decide which of the two is best for you after some serious range time. I contacted Federal's principal chemist, Joel Sandstrom, who has been with the company since 1990, to get the details on the new Fusion primer.
"We thought we could build a better mouse trap" Sand-strom said, via email. "Our development goals were two-fold. First, the primer had to be capable of igniting all blackpowder substitutes at maximum moisture uptake, and the ignition had to be cool enough to minimize or eliminate the fouling ring. The project lasted six months."
A standard 209 primer, as Sandstrom and muzzleloader shooters everywhere knew, delivered too much heat too fast. The new primer would have to generate less overpressure. Though "softer," the primer would still have to be hot enough to guarantee ignition.
"This track is exactly what was accomplished years ago with the Federal GM205M small rifle match primer," Sand-strom said. "The primary ignition component is still based on lead styphnate, which is the standard primary explosive used in small arms primers, though Federal's formula is unique. The remaining components--some standard, some new--have been adjusted to produce less pressure and deliver more hot particulate."
With the right primer compound in hand, the nominal charge weight was determined and extensive testing started. That data was used to tune the primer for ignition sensitivity, pressure, velocity and time-to-peak pressure.
"We also added the matrix of conditions to the design of experiments to account for a specific propellant source and minimum/maximum moisture uptake," Sandstrom said. "The primer is designed for all blackpowder and blackpowder substitutes used in muzzleloader applications. It took longer than expected, but in the end we learned a lot about blackpowder substitutes and ignition requirements. It was a fun development process."
Aren't you glad smart guys like Sandstrom approach their work with such enthusiasm?
Using the new Fusion or the old Winchester Triple Seven primer with newer, better propellants will likely result in tighter groups, less fouling and the near elimination of that troublesome crud ring, though I still swab between shots at the range. A quick test with a .50 caliber saw groups tighten a quarter-inch when using Federal Fusion or Winchester Triple Seven primers over standard 209s. There was no statistical difference between the Fusion or Winchester primers. Keep in mind, though, that some propellants, most notably Blackhorn 209, require standard primers for reliable ignition.
While small, the primer is a critical component in the muzzleloader firing chain. It can make or break accuracy and make your life easier.
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|Date:||Aug 1, 2010|
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