flowers of sulfer, potassium nitrate and ground up daddys kingsford charcoal....
I did the same thing...the St George family who owned the drug store down the block, looked at me kind of weird when I asked to buy the components....mostly it just burned as I probably didn’t make it right...
I bought it every couple of weeks, I made firecrackers and rockets out of it!
I used to get 50 cll. shells from the surplus store, fill them with powder, use a straw filled with powder, set them on a ram[ and fire them.
One firecracker I made was a little large, it broke windows in 3 neighbors houses, it was 2 feet tall and 6 inches in diameter.
Gun powder is not an explosive - meaning that the burn rate is less than the speed of sound. If your mixture burned, it probably qualified as gunpowder. The only reason black powder works in a gun is that the volume of gas produced increases in pressure because it is contained / directed.