The 205M primer drove his 6mm, 70-grain bullet downrange about ten feet! In disbelief, after the match, he experimented and found relatively consistent results, in his unusually small, tight-fitting and chamber-sealing cases, sized to provide only modest neck tension, using moly-plated bullets in an unusually smooth bore, primer force always drove bullet through barrel, with enough velocity to move it several feet before it reached the ground.
How Blackpowder Differs from Smokeless Powder (in response to primer blast)
In the ways that it responds to the blast from a primer, blackpowder has two significant differences from smokeless powder (an interesting term for a product that is neither smokeless nor a powder!). First, blackpowder might ignite in response to a somewhat different amount of heating. Second, while smokeless is significantly plastic and particularly tough, blackpowder has very little strength or plasticity. Hence, while smokeless can withstand the intense shock of the primer blast relatively unscathed, blackpowder will be massively fractured by the shock associated with any conventional primer generating sufficient energy to produce rapid ignition. This fracturing will reduce or possibly eliminate permeability – at some point, the fracturing front may extend forward of the effective ignition plume so that the remaining charge cannot ignite directly!How far this fracturing propagates into the blackpowder column is an interesting question and may alone explain why "hotter" primers often generate higher blackpowder load velocities – more of the charge pulverizes and hence more of it burns faster. However, this hypothesized "Pulverization