Then a deliciously dangerous thing occured to me. The reason you don't EVER use the finer grain FFFFg pan primer powder as a main charge in a muzzle loader is that you'll blow up the gun. But this is the same reason you don't EVER use smokeless powder to charge a muzzle loader. I knew that the coarser grain FFFg wasn't going to give me enough power to produce impressive results in such low volumes, but I really wasn't sure what would happen if I tried using the pan primer powder.
So, I asked a guy I know who has long experience with black powder and he basically said, give it a try. I loaded up 15 rounds of 9mm Largo with 15 grains of Swiss Null B FFFFg pan priming powder -- the fastest burning pan powder in the world -- topped them off with .356 inch diameter 100 grain KIR "Minie ball" type bullets, and selected the rusted and worn out Astra 400 "Bad Bore" case study barrel for test firing through a tough 1930s vintage Astra 400 (with a fresh recoil spring from Wolff gunsprings).
A single loading of 9 rounds ran through the Astra 400 flawlessly. The gun behaved exactly as it does with standard smokeless loads. It didnt' even produce much smoke, for that matter. The Bad Bore Minie Ball bullets stayed stable and produced decent accuracy. The fired casings showed no high pressure warning signs. And the gun looked fine on inspection during cleaning.
The implication of this test is, in my view, that black powder can be used as a smokeless powder substitute under certain conditions and within undetermined limitations. With black powder being something that can be made with the crudest of materials and tools, this means there's no practical way for gun prohibitionists to choke off ammunition by regulating or taxing gun powder. With brass cases littering the countryside in wild profusion, cast or recovered bullets just as easy to source, and black powder about as easy to make as moonshine, there's really nothing but the primers to potentially prove an Achilles' heel in centerfire cartridge availability. Personally, I suspect that if heavy restrictions or taxes are placed on ammuntion we're going to find out real quick that priming compound can be made by anyone currently crazy enough to run a meth lab in their trailer park. And when we get to that place, the common centerfire cartridge will be grudgingly and universally acknowleged to be a sort of eternal flame. Whatever your political or social viewpoint is, I'm here to tell you that I can shut up and shut this website down today, but guns and ammo are here to stay. Accepting that simple fact would help us all as we struggle with the national debate over gun prohibition, its illegality, and the potential consequences -- both likely and unlikely.
There is more info on this test under the related innovation and invention tab found on the KIR home page.
I have to warn that this is a very specific and limited result that would be impossible for anyone to exactly replicate, due to the unique nature of the test barrel. The oversized bore of the test barrel probably helps to prevent over-pressure from black powder fouling. The test was limited to 9 rounds. And the freebore, or leade, in the test barrel is very, very long. This long leade should greatly reduce the peak chamber pressure, by allowing the expanding propellant gasses to drive the bullet under very low resistance for a considerable amount of the distance and dwell time of the bullet's travel down the bore.
To be absolutely clear: If you were to try to replicate these results, you could easily detonate your gun, killing or seriously injuring yourself, and/or others. The behavior of similar loads fired through different or un-damaged standard guns is unknown to me. This same load could very well detonate the chamber of a standard Astra 400 barrel that retains its factory .355 inch diameter bore and has the factory standard leade, allowing for essentially NO freebore at the chamber end of the bore to help keep peak pressures low. DO NOT try this unless you have the experience, facilities, and willingness to safely and remotely destroy guns by overpressure. The risks you take are yours and yours alone, and this kind of experimentation is exactly the kind of thing that can get you killed or get you stuck in a dirty nursing home drooling on yourself for the rest of a miserable shadow of a life left to you by brain injury.