I was testing a new barrel design in my backyard last Saturday and the whole thing just blew apart at the seam. Luckily nobody got hit but it scared my neighbor pretty bad. Turns out I used the wrong type of cement for the fittings - needed the heavy duty stuff for pressure rated pipe. I'd been building these things for like 8 months and never had an issue before. Anyone else learn a hard way about material specs on homemade launchers?