You may want to research the Spanish manufacturer Mendi. From what I see in your photographs, your gun appears to use many nearly identical components that my Mendi blunderbuss uses, such patchbox, lock and hammer, breech plug, butt plate and even the stock wood is similar. Below is what I previously posted a few years ago on the Mendi.
‘I have the ‘budget’ version blunderbuss (picked it up in an estate lot purchase) made by Mendi. 13-1/2” barrel (including the bell), percussion, grade 2 pallet wood, ‘24 Cal’ whatever that means (close to 26 gauge at .56” bore), etc.
Ok, the gun is a blast to shoot. The kids, large and small seem to love it. I bring it out on the 4th or anytime there is crowd and need or want an obnoxious noise maker. Put balloons up a few feet in front of the kids, load 30/50 grains or so of whatever is ‘excess inventory’ powder under a cottonball, and enough ‘stuff’ comes out of the muzzle to pop balloons, make smoke and a big boom. The kids think they’re Captain Jack and line up to shoot it. Good chance to teach gun handling safety and introduce young (and old) to ‘traditional’ muzzleloading. Unfortunately, it is as close to it as many will ever get.
Before you try the above load, get clearance from the grounds crew. Brother in-law’s bride had a fit trying to keep up with cottonball fuzz and ballon fragments in her back yard.’
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