Hammer pilot valve with QEV

[KAspud]

Hi, i'm new relatively new to this but I'm planning to build a QEV or pistonvalve airgun with a hammer valve as the pilot, allowing semi-auto firing. Any suggestions on chamber volume ( i'll use 1/2 inch copper barrel) or general help will be greatly appreciated

[Gun Freak]

I'd say about 67.634 liters will be sufficient.

[DYI]

You'll want 12.38 times the volume of a piece of string ±0.5% for optimal k3wlness...

[mark.f]

Don't forget that chamber condensation (being a liquid) is virtually incompressible and it's average volume should be subtracted from total chamber volume during design.

[mattyzip77]

I would say multiply your barrel width by the length and then divide that number by the size of your q e v!!

[Crna Legija]

umm tough one but, if you have a spare fuel tanker on hand it should work out as the tank.



or maybe give use more info

[jhalek90]

[Brian the brain]

Forum rule nr 1.
Not nr.2...

1!

Don't be a jerk.
Keep the flaming to a minimum. Remember, you were a noob once too. Also, keep in mind that this is a text-based medium, and as such, sarcasm does not always translate well.

Boys!
Behave yourselves.


now..

Hi, i'm new relatively new to this but I'm planning to build a QEV or pistonvalve airgun with a hammer valve as the pilot, allowing semi-auto firing. Any suggestions on chamber volume ( i'll use 1/2 inch copper barrel) or general help will be greatly appreciated

Small chamber volume would give you very few shots and pressuredrop between shots is drastic.
No matter what pressure you intend to use a basic principle is that for multishot you want as much volume as possible.
Only you can decide how much is too much.
I like both performance and looks so I generally go as big as possible without making it look bulky.

Using high pressure allows you to get powerful multishots from a relatively small package.
But size still matters at high pressure.
The bigger, the better.
Big means better power and less dramatic pressuredrop.

Now another thing that comes into play with a hammered QEV:
The pilot can be used to tune the powerlevel.
A strong hammerspring and heavy hammer give what I like to call "deep"shots, the reverse will give you "shallow"shots.
The amount of gas expelled by the QEV is closely related to the pilotvalve settings in this kind of setup.
The very size of the hammervalve also makes a difference.

All this makes it very hard to give an exact answer to your question.
Leaving out the information on pressure, barrellength, ammo, personal taste and last but not least your expectations on performance makes it downright impossible.

Hope this helps.
welcome to the forum!