ok to summarise then, it looks as though i need the following parts and materials:
+ 12" x 4" SCH 40 PVC Pipe
+ 21.25" x 2.5" SCH 40 PVC Pipe
+ 4" (SCH 40?) PVC threaded cleanout adapter
+ 4" (SCH 40?) PVC threaded cleanout plug
+ 4" (SCH 40?) PVC Couping
+ 4" x 2.5" PVC Bushing
Plus sparker etc.
If you all agree then i thank you greatly for giving the advice that you have given me and when ive built the cannon i shall definately post a pic and maybe a video to show how it went.
Also if you guys could just clarfiy, the items above with (SCH 40?) written by them, all need to be SCH 40 or not?
Many thanks guys