Piston Speed

Cannons powered by pneumatic pressure (compressed gas) using a valve or other release.
squeaks
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Ok, here's a question I've had for a long time. What is faster, a chamber sealing piston or a barrel sealing piston?

Thanks for the help in advance
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Hotwired
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Piston flies back at the same speed in both cases, a barrel sealing one could be said to have less dead volume between the compressed air and the barrel and so fire a smidgeon faster.

If you're chucking a potato stick the difference of 1/20 of a second is nothing to burst a braincell about.

In fact your reactions are more likely to give a firing time delay than 150psi air expanding.
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POS
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I think a chamber sealing valve is harder to mak though. Try a diafragma valve. That is even quicker, cause the diafragma isn't as heavy as a piston.
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boilingleadbath
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1/20<sup>th</sup> of a second <i>would</i> be something to worry about, considering that's longer than the projectile spends in the barrel!
However, the time difference between a chamber-sealer and a barrel-sealer of similar porportions is closer to 1/500<sup>th</sup> of a second. (a barrel-sealer opens in about ~1/300<sup>th</sup> of a second)

(generaly, we measure these times in milli-seconds; a millisecond is 1/1000<sup>th</sup> of a second. Using this system, we would say that a chamber-sealer opens 2 ms slower than a barrel sealer, which means it opens in 5 ms [as opposed to 3].)
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Hotwired
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Ok, fine I haven't looked at GGDT very closely or very much.

I was trying to make a reference to the fact that the time difference between the two valves firing is very small and human reflexes are more likely to make a difference.
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I know mine is fast enough to keep me working on it! But it's worth it, i got a couple shots off today.
squeaks
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Ok, if barrel sealing valves are a little faster and less complicated why does Joel make his a chamber sealing piston?
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POS
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cause he can ?
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