In the for what its worth department, here is a Black Powder Buckshot experimental load I put together a few years back. While this load could be further refined, it shows just what applying modern loading concepts to the oldest form of gunpowder can do.
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"I had a few new Cheddite 2.75" primed paper hulls left from another project, a partial box of Hornady 0B, some old Federal plastic shotcups and some .135 over powder card wads. Lets see now. Well 105 grains, (3.85 drams), of Goex FFFg went into the hull, then over powder wads, a Federal shot cup, ten 0B pellets, PSB buffer, finished with a thin OS card and then roll crimped. Oh, forgot to mention the pellets were stacked in layers of two to let the choke do its work.
Well finally got to touch off this throw-together load at the range. From an 18.5" Mossberg barrel with an old style Winchoke tube marked Imp. Mod., that black powder charge loudly belched forth fire, smoke and lead. Did I mention LOUD? When the smoke cleared, those ten 0B pellets had produced a 10" pattern some 25 yards downrange with 6 of the 10 pellets crowded into a 5" centered pattern core!
Old and new, fire and smoke, with a tight pattern to boot! "
Ref:
https://wethearmed.com/shotguns/loading-buffered-buckshot-with-black-powder/