I've done things like that many times with no ill effect.... you just need to know enough to set it off at a safe distance. I built the most awesome oxy acetylene spud gun you ever saw once. The plastic tubing was reinforce by cutting the little flange out of couplers so they could slide over the pipe, and covering it entirely, then dropping the works into a piece of steel exhaust pipe. I set it off with a spark plug in the bottom, and had a bolt through the works to drive the spud down to for consistent chamber volume. I would light a torch and adjust the flame properly, then snuff it out on my boot, and insert it into the spark plug hole for a suitable amount of time, then screw in the spark plug, sand bag the spud gun in place, and touch it off from about 20' away. It would break a sheet of half inch plywood 100 yards away, and we experimented with ballistics, trying to lop spuds into a neighbor's yard 1/4 mile away...... we succeeded!! This was way out in the country. We got comfortable enough that I would hold the barrel down with my foot... the barrel being the outer steel pipe after aiming it. My buddy would touch it off with a wire to the coil (breaking the circuit just like poiints). His mother had grown a bunch of spuds we classified as "shooters"....... too much manure in the garden, and they came out scabby. About 2/3 of the way through the wheelbarrow of spuds, I was standing with my foot on the barrel and Bob touched the thing off, and along with the spud, is spewed a pile of plastic fragments!! No harm done, nobody hurt, but it was the end of my spud gun adventures.
H.W.