This is only a guess mind you. The Knight Original Disc I shoot used the orange primer jackets. As some understand, the old orange primer jackets just sit up against the face of the breech plug. Unlike the red Knight primer jackets that almost attach to the shape of the breech plug. Here is what I suspect.. As the primer was ignited in the jacket, the spark ignited the main charge, as designed. This Blackhorn main charge then pushed backward into the now closed bolt of the Knight Disc. So all this back pressure hit the orange disc (which became destroyed by the way) and was basically held there between the primer jacket and the face of the breech plug.

It was funny because the first plug looked like someone took a small chisel and knocked little dents and chips out of the breech plug face. And I threw the first breech plug away, because it would not consistently fire the rifle. Well I am guessing the fire channel was carbon coated and not letting the fire through. Which might have even increased the damage to the the breech plug face.

As the second breech plug started to encounter the same problem, I ran out of the Blackhorn 209. Now remember, I was shooting Blackhorn 209 before most people even knew it existed. It was something really new. I tried the powder in a number of different rifles. And discovered the hard way which rifles would not shoot Blackhorn safely.

I recently ordered five more canisters of Blackhorn from Ed's Gun Shop and so when it arrives I am going to put it through a battery of side by side tests with other powders and see if it really is IMO a better powder.