2240 Valve mods

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Topic: 2240 Valve mods
Posted: 10 Jun 2025 at 9:42am

There is one more mod that i had done which seemed to me made difference and that was a hollow probe bolt. ( Its such small and non intrusive mod i forgot about it)
Pauly5 was kind enough to turn one up for me.
I had replaced the original bolt with a extended probe version allowing the pellet to push past the transfer port,
I worked fine but the hollow probe really ended up being a good move.
It's contact point is wider and sits better against the inside of the pellet skirt, but i think the main thing is it directs the pressure strait to the back of pellet which means the pellet has to start moving before the gas can keep expanding and as the pressure is directed to the inside of the skirt it flares the skirt better or quicker than having the small amount of space to start expanding around the probe first.
What ever it is, i noticed the difference at the time i installed it and wont be going back to a standard bolt or extended probe bolt for any pump or co2 air gun i get in the future.
A small and subtle change that im glad i made.

Edited by kruzaroad - 10 Jun 2025 at 9:47am

Kris

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Posted: 10 Jun 2025 at 2:03am

kruzaroad wrote:

The question would be, i think is it putting out enough power as it is to do what you need it to do.

Yes, your dead right.
So in my case modifying the valve would be of no real use.

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kruzaroad

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Posted: 10 Jun 2025 at 12:06am

The question would be, i think is it putting out enough power as it is to do what you need it to do?
Power for the sake of power isnt always the best move.
My 1322 doesn't have great power, but its a bird gun. For tree shooting and at that it excels. A longer barrel and steel breech,scope and really thats is enough.
Have a rifle for further distance larger critter.
It will never be a primary weapon for hares or possums and doesnt need to be. It fills it role very well.

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Posted: 09 Jun 2025 at 11:24pm

I think a 12-14 inch barrel is the best to use with the modded valves,

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Posted: 09 Jun 2025 at 11:21pm

Thanks, there's plenty to think about.

kruzaroad

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Posted: 09 Jun 2025 at 3:28pm

If you want to the math for the volume of your barrel here's a blurb on expansion rate
The liquid-to-gas expansion ratio for CO2 is approximately 535:1. This means that for every unit of liquid CO2, it expands into 535 units of gaseous CO2 when vaporized at room temperature and normal atmospheric pressure.

Heres a pipe volume calculator which you can get an approximate volume off. Due to rifling its not going to be exact but should get you in the ball park. It will take mm and inches at the same time so you can do the pellet in mm and barrel in inches
https://www.servicetitan.com/tools/pipe-volume-calculator

Edited by kruzaroad - 09 Jun 2025 at 3:44pm

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Posted: 09 Jun 2025 at 3:21pm

I will agree with the longer barrel and from experience heavier pellets.

Mintie is a CO2 wizard.

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Posted: 09 Jun 2025 at 3:14pm

So i been looking at 2240 valve on line out of curiosity,
It would seem you can buy a better flow valve from boss. A better transfer port to barrel, up to 25% increase in volume flow claimed. Also a stronger hammer spring to keep valve open longer or weaker valve return spring.
Seems the longer barrel is the number one thing to do.
Im assuming as co2 will only pressurize to a certain pressure (not taking heat and cooling affect into account) that goal would be to get enough co2 into the barrel to keep it expanding for the duration of the pellets travel along the barrel.
Thus there will only be so much that can be achieved in actual power gain and that max power is created by having a long continuous push that doesn't stop till after the pellet leaves the barrel. Not a get the pellet going and let momentum carry it the final part of barrel, or a weaker push as the co2 slows its expansion due to decreasing expansion pressure.
Only issue i see would be the gas flow around the pallet as it left the barrel. Your crown would want to be in good nick to encourage even distribution of escaping gas so as not to upset the pellet.
It would also seem you can actually take some metal out of the head of the valve to help volume.
Also the thinning of the valve stem as mentioned above.
Nut as i say, this is from web research.
Hopefully the ppl on here who pull these co2 pistols apart can verify this

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