Tell us about yourself!
Packing gunpowder gives less space for each piece of gunpowder to burn, and it needs space for the exhaust gases to go, so it doesn't burn when there's no space for gases to escape, aka when it's packed. It only burns on exposed sides, meaning it burns slower. There won't be an explosion without a way for gases to escape because it won't burn.
I did this in my project. It's not hard, but the poly wire is nothing but polution and cyanides from burning that. It's really just shorting the whole system and you'd be better off with some easy-peasy steel wool.
Paper Rocket (Really Flies!)