Vintage cap gun to potato gun conversion...

[musket]

Hello all...my first post! So....I have a long barrell musket/rifle cap gun I want to make shoot potato. It's made of metal and wood. My thought is to put hairspray in the barrell then use the spark from the cap ignition to ignite what shoots out a piece of potato I'd wedge in it's barrell end. My questions. First...is this safe? I'm not making a pipe bomb that would go off in my hands am I? Must the piece of spud go all the way down the long barrel or can it sit at barrel end? Hairspray ok and if so...how much? Finally popping a cap (gun powder) that close to a hole with accelerant on the otherside...safe? Many thanks!