My husband bought a black powder gun kit and when he was done, he didn’t know if it would blow up or shoot...he stood behind a large tree and used his left hand to shoot just in case he made a mistake in building it...LOL he said he could get along without his left hand but not his right hand...he build it right, didn’t blow up and take his hand off....
As long as you’ve got the right amount and right type of powder they’re safe enough LOL. Oh and best part is they aren’t on record :>}