Thanks for the input. I tried all different spray times. I did put the grill ignitor in the chamber. I'll try putting screws in.

How far apart should I put the screws?

What would a good fuel be?

This is my first attempt at building a spud gun. I have 4" x 15" chamber, a 2" x 5' barrel, and a grill igniter. I'm not sure how long to cut my barrel(C:B ratio I think), or how much fuel to put in. I've tried bug spray and starting fluid, and only got it to shoot once with bug spray. I tried all d...