Fork in the road here...

[Sticky_Tape]

Yeah be reasonable you can't eat a baby!

Note the word (luncher).[/b]

[Blitz]

I bet Blitz is really regretting using that expression in the title now

Comes with the territory, I found it amusing actually.

Well, after some review and analysis of parts I already have on hand, I felt it'd be cheaper and more rewarding to go pneumatic. If I want to make a huge combustion launcher, I'm sure I can scrounge up some large diameter pipe somewhere and I'll just worry about it later. Although like schmanman said when he was considering upgrading his SWAT, switching to more 4" volume means higher pressure, and my compressor can handle 200psi. But what the hell, I'll stick with 6" anyway.

I do need to devise a breech of some sort however, which I think would just be fine with a set of metal cam-and-groove hose couplings on a floating barrel. I'll start another post with my project.

[SpudMonster]

If you fuck in the road, you'll get arrested for indecent exposure.

[starman]

Being a combustion leaning guy myself, I would like to throw my hat in your ring to say ....go big combustion. I want to challenge the notion that a pneumatic design will automatically offer you a more powerful big-bore spud cannon, assuming that's what you're looking for of course. Pneumatics will ultimately win against a burst-disked 1x combustion but you'll have to use big airtank, a lightening fast piston, and large psi to do it.

A feature almost totally ignored on 1x combustions is the simple addition of a burst disk union or camlock burst disk option. I have been getting noticable power and speed increases using the burst disk below. These burst around 80 psi and offer amazing results over a humble standard advanced combustion.

Even using a modest 30 psi disk will show a noticable performance improvement. I'm using the male camlock plugs shown below as a barrel stump by itself to use in my noise cannons I'm building.

With that big chunk of 6" pipe you have, you could build a whole fleet of big combustion chambers.