I had my fuse hole enlarged from a small pin hole to 7/64 matching the fuse that I bought using some DuPont 7625 smokeless powder as a test. Ignition but main burn back out of the fuse hole and not enough pressure to eject the paper wad. I'll make some black powder in a few days and try it again but suspect that seeking closest point of least resistance it will again come back through the now proportionally too large fuse hole.
Did you have the dowel plug/shot in a fabric patch for a sealed fit? BP Muzzle loaders place a fabric patch over the bore, set the ball on that , give it a partial set down, cut off the remaining fabric patch, and then firmly ram the ball against the wad ahead of the powder charge. When I get my powder I'll give that a try using your dowel instead of the steel ball bearings that I have and would not be able to worm out if it failed. Wood . . . yes, feasible. PT=2
I glued an #26 wire into channels ground in the wood plug and bend ends over the plug at the chamber end glued with gorilla glue and it fit tight in the bore so no patch needed. The wire was there so I could retrieve the plug if it did not fire. It was not loose but it was not totally tight either. the glue residue kept the plug in the chamber.
The drawing helps to understand your approach. What is the diameter of your fuse hole? Maybe a small screw with the copper wire on the front end would work and not give you the problem of the glue attaching itself to the bore. Just wondering. It would also give some more mass to the projectile.
After receiving the firing kit from Miniature Cannon Technologies, LLC. including both black powder and their small .177 caliber balls I pulled out by reloading balance to measure both the grain weight of the small scoop measure (flat and rounded) and the balls together with measuring their diameter. I used this to compare with the ball bearings that I wanted to fire in my cannon by scaling things up in a slow safe manner. They also sell and have instructions for a 25 caliber and the related load. All of this together gave me a starting point for my own initial load/shot. Not a full load but 2/3 by scaling their 25 caliber to my 9/32 inch ball and slightly larger bore. An initial mission was to fine a fabric fine enough to wrap the ball properly onto the following sequence: fuse, powder load tamped firm, small paper napkin piece wad, wrapped ball and a final very small napkin wad. I clamped the barrel in an F-clamp and placed the barrel bore on to a small sandbag with two more behind the breach for recoil. I was firing into plastic tub with some heavy linen cloth folded over numerous times. Lit the fuse and stood behind an yard recycling barrel for safety and did not see the shot but it sounded like a 22 pistol. No noticeable recoil drift, everything in place and the ball creating a depression, still wrapped in to the cloth with bout a 1/2 inch indentation. I was most concerned about the 7/64 fuse hole size to the bore but the ratio was similar to the .177 inch cannons with their 1/16 inch fuse hole so it was not a significant firing problem. The fuse is the same 7/64 diameter as the hole so it is a tight fit.
Here is a photo of the barrel just after firing, back on the bench, cleaned and the loading items laid out before I took out the started carriage for continuation.
The barrel is just fine. It is the carriage that I will complete and then see about making another for the same barrel using a different parts and assembly than in the first but there were no standard carriages so it would be in how much detail that I want to take on with the very small threaded rods, bolts, and square washers with long holes for passage. I could get around the long holes by using three laminated layers with gaps between portions in the innermost ply covered by solid outer plys. No drilling what way, just more cutting and assembly. After final connections and the clamps for the trunnions are in place I'll fire it again that way. Then if all goes well I'll attach the breach restraining and side tackle lines and blocks. Shipboard gunship style to a forward bulkhead which would need to have its own bracing for the recoil which normal models don't have to deal with. It could be an aluminum angle bent and overlaid with faux planking.
That 45 makes my smaller 5/75 inch bored to fire a 9/32 bearing with black powder. I turned the barrel about 45 years ago from a
high strength steel rod. It works very well but the carriage is still to be completed. I used an F-clamp and some sandbags to elevate the barrel and control recoil. Fired it into a plastic tub with folded cloth inside as an initial trial with minimum charge when I can now work up noting the ballistics along the way to where I will call it max. I started with plumbing pipes and opened firecracker powder back in the 50's in Montana where all things go as long as you survive . . or back then 
PT-2
Now that is an eyecatching boat!!! Happy sailing. PT-2
Thanks. I'll keep you posted as part of our guncrew. PT-2
The black powder components and instructions arrived today. It seems that it is primarily intended for fireworks so it may be not efficient for the cannon. I can always purchase some muzzle loaders powder from the local shop which may be less expensive than the close Cabellas. PT-2
