You can search these forums for "honking" for a number of posts about the problem.
There is also a brief page on the wiki at spud_wiki/index.php?title=Honking and spud_wiki/index.php?title=Sprinkler_valve_modification

That is TRUE, in 35 years I never installed a PVC gas system. I have installed Polypropylene. PVC is not used on gas because it is FLAMABLE. SCH.40 PVC IS pressure rated to about 220lbs and SCH 80 to about 320lbs. OF course the Explosion of Propane probably creates more than those pressures, which ...

You could also just use a neodymium magnet if you are just trying to keep the BBs from rolling out'a the barrel.

Another challenge is that the chamber pressure probably oscillates a fair amount (pressure goes up when a bb is actually in the barrel, down when the barrel is empty). One approach might be to start with ROF and muzzle velocities for a BBMG some has already built, use that to calibrate GGDT, then mo...

Welcome to the forum!

Post some pics and specs, people are usually glad to help (or at least chime in with criticisms )

If you want to be taken seriously quit using the stupid name "HHO". There is no such thing. You are using 2H2 + O2.

Hi, I was wondering what the best ignition (other than a stun gun) is for spud guns. I generally use 2 nails and the piezoelectric thing from a bbq lighter but I have heard that grill igniters work better. So if anyone knows of any other (under $20 ideally) ignition sources please let me know. "Wor...

If the mix is right then the spark is wrong. You may have have an internal short in the spark gap.

Either you aren't actually getting a spark or your mix is wrong. Pretty much any electrical spark should ignite a correct mixture. (Though at high compression ratio's it'll take either a higher voltage or a narrower gap to get a spark.)

The problem with Huricane's design is that the next BB inhibits air flow needed to for the previous bb. I think you want the cam to keep the next bb in magazine, instead of the barrel until, the first bb has cleared the barrel.

Wouldn't it have some of the same problems as a ball valve? In particular, slow opening time?

Regulators don't vent to relieve pressure once they are set. The only time they vent is when you drop the set pressure. If you aren't fiddling with the pressure it wont be venting. I don't think using a regulator is the norm. I think it is more common to assume a particular pressure in the propane t...

Should work... but 1000 ft*lbs of recoil is pretty significant.

That looks like a good setup. You might need to adjust things a bit but your setup will probably work. I went with the open design to avoid having the chrono jig act like an extension of the barrel. The 1K resistor should be about right and overall the chrono setup is pretty insensitive to details l...

I left out one more source of error and uncertainty; the accuracy of measuring the distance between the detectors. An advantage of a longer detector is that the uncertainty in that distance has a smaller affect compared to a shorter detector.