yes at atmospheric pressure it reads zero

http://i584.photobucket.com/albums/ss281/outdoorsjd/120708_0006.jpg

http://i584.photobucket.com/albums/ss281/outdoorsjd/120708_0005.jpg

http://i584.photobucket.com/albums/ss281/outdoorsjd/120708_0004.jpg

http://i584.photobucket.com/albums/ss281/outdoorsjd/120708_0003.jpg

http://i584 ...

1/2" pipe, 3.5" long with a pressure of approx. 90PSI but it won't fire at that (what ultimatespud calc spit out) if I go down to like 25PSI it'll fire though.

I used this idea in a combustion cannon. It does not have a ball valve. I have it rigged up with elastic bands to return it to the starting position. i would put pictures on but I cannot get them of my phone at the moment

This is exactly what I did in a nut shell

I have an air ram on it to simulate the recoil of a field gun. Its hard to describe. Look at this : http://www.spudfiles.com/forums/ways-to-add-a-recoil-system-t24152,start,15.html
It pushes the whole barrel and chamber backwards upon firing on a set of tracks with elastic bands to return it to ...

11" 3" sch 40 chamber, Approximately 50" 1-1/2" sch 40 barrel minus the air ram.

I used the spud tool from ultimate spudgun and By the calculations, the meter is way too big and there is no ignition of propane. I will try adding a chamber fan and see if that helps.

Sure, where did ya get your stun guns? Always figured it'd be nice to have a stun gun ignitor. Prolly will need it in the future, I want to make a 3" barrel field gun essentially. Still workin out the kinks and designing it. Eventually I am gonna build a 1/2 scale soviet SU-152 and this is how come ...

But, the electronic ignitor works great and I got a discount 'cuz I work at the hardware store I bought it from

Lucky......the ones I can find go for $30 on the cheap end, but I always keep my eyes peeled for a good deal at gun shows and other festivities

still the ignitor was half the cost of a stun guns that i can find. I'll try to get some pictures up, they are on a micro SD card in my phone and I think I misplaced my converter to SD. I'll see if I can find it

I am using an electronic grill ignitor with 2 points of ignition

Yes I have adjust propane % up and down and have figured out what works best. I just am not getting the power out of it. I used to be able shoot potatoes, walnuts, and ear corn so far you could barely see it, now it just kinda lobs it not really up to it's previous ballistic performance. I have an ...

Well, I made a propane meter for my cannon. I am having a problem with get enough.......how to say it....uumph out of it. It really doesn't crack like it did with hairspray or shoot as far. I think it might be that the chamber size is too small, a .87:1 chamber to barrel ratio. It really cracks with ...