Hey spud gunners

I got an issue. My top keeps getting stuck. I tried a few different greases but none seem to help. I have tried cutting down the threads on the cap but that didn't help, actually made it worse and unsafe. Got any ideas or lubes that do work? Any help would be great. Thanks and ...

I would like my combustion chamber to 4" in circumference. How long would my barrel have to be for .7:1. I would like two diameters for the barrel to be 2" and 1.5"

I will attempt to do the equation, please correct me if I am wrong.

sch. 40

4" diameter chamber at 7" long = 87.8 ci
2" diameter ...

Thanks hi for the calculator!

Ok so now I have a rough outline of what I would like for dimensions.

4" chamber in diameter, that is 18" long is 226.28 inches squared.

Now if I put a 2" diameter barrel that is 36" long I have 113.14 inches sqaured.

So in order for my launcher to have a 7:1 ratio ...

Hi I am a rookie builder and I want to make the most powerful gun. I know that 1.5:1 is the best ratio. Can someone calculate the math for me so that I can see the equations to help better understand. I want to try different sizes. I would like to try a 4" ID and a 3" ID chambers. I would like to ...