A friend of mine was a volunteer guide at Fort Fisher Military Park just south of Wilmington NC. Every so often, tourists would ask the proverbial question about shooting smokeless powder (Hey, its black, they would say) in original or replica muzzleloaders & and cap & ball revolvers. So, he took one of his own well-used revolvers, and loaded the top chamber with smokeless powder from a 9mm pistol target load, (1.5 grains by weight of Bullseye Powder). He set the revolver in his outdoor brick fireplace, and put two heavy steel plates to cover the two openings in the grill, and stood back 60' with a string, and pulled .
If you need a graphic image about the strength of smokeless powder, here it is:
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