SUCCESS!!!
24 shots today with 100% ignition on the first strike. There were two different batches of 12 rounds each. The tubes for both were rolled with borax-soaked paper, wrapped with a layer of silk gauze, and had the rear rubber disk NOT glued to the percussion cap - rear end closed with the stick-on daisy, and it's petals held down with the over-layer of silk. Both used something very close to the regulation charge by volume, but of Triple 7. Yes, that's hotter than black, and again, I touched off the first one reaching around a block wall. Gun did not seem to mind in the slightest.
The more successful batch used Gorilla Glue to attach the silk and had 0.4 of a grain of real black powder inside the cap. Ignition was instantaneous on all, and I found these on the ground about 15-20 feet in front of the muzzle:
Very largely intact pieces of cartridge casing with silk and daisy sticker still attached. Most of these had the cap assembly sucked out of the bore. One or two even managed to get the rubber disk out, but for the most part, that was still left behind on the bolt head or in the chamber.
The second batch of rounds had no powder inside the caps. Most of these had a VERY slight delay between strike and boom - about what you might get from a well tuned flintlock, maybe a bit faster. The silk was attached to these with good old Elmer's schoolroom glue. These did not do nearly as well at clearing debris from the bore, and I had to poke a patch to get the caps and a couple catridge body chunks out.
It might be that a slightly harder silicon rubber would do better for the obturator, for expansive pressure is something you are not short of. Silicon gasket mixed with chopped nylon fibres might be worth a try.
Accuracy is going to take some work. With the sights on the lowest setting, it's hitting about 10" or more high at 100 yards, which could be worked with if the gun wasn't ALSO hitting a couple feet to the left. If this gun has a provision for windage, it hasn't made itself known yet. Not going to do anything permanent to the sights until we generate a load that actually GROUPS and gives decent chrono data.
As to the gun itself, my home-made bicycle spoke needle worked flawlessly and held up fine. The silicone obturator sealed perfectly, although it may have a slight bug to work out:
The problem seems to be that as the chamber gets fouled, rounds do not insert as easily. Since you then have to shove harder on the bolt to get the round to chamber and the bolt to close, the bolt head gets pushed back and the obturator obturates. I think the rear of the obturator got steadily scissored off between the chamber and the face of the bolt body. Now that the problem section has been removed, I doubt it'll be a problem from here on out. The rest of it appears to have held up fine.
Regarding the Callibaud round: I received an automated reply from the Paris museum several days ago stating that they had received my email and that a reply would be forthcoming. Still waiting on that. I've got a couple more archival contacts I'm going to try rolling the dice on.
Rifle deer season starts in 8 days, so this will be the last of the shooting reports for at least a month, but I'll be here for the discussion and data updates as they come.