Newbie pcp question on bleeding air

[Elgreco]

Hello Everyone,

I went all in on PCP rifles ( been shooting slringers for years) and bought 3 different rigs (used) that are on their way here. Long story short, one of them is three way adjustable in terms of hammer spring, transfer port and regulator. 

Assuming that I start with a full psi tank and everything adjusted from the factory down the middle, and I want to experiment with higher fps I can start dialing up the hammer, regulator etc..

Now if I want to start dialing things back down I can do that with the hammer spring and transfer port but not with the regulator, am I right?

Meaning that to start dialing the regulator down again ( in order to shoot weaker) there has to be no air in the tank. Please correct me if I am wrong, just wanted to make sure I don't damage anything.

Also if that's the case ( where you have to have an empty tank to dial down the regulator) do most people just dry fire the gun till it gets empty? ( in my case I think that particular rifle has a bleed valve for the tank). 

Thanks for helping a total newb

 

[nervoustrig]

Correct, adjusting the regulator’s setpoint _downward_ while it is pressurized runs the risk of damaging its valve seat.

In the overwhelming majority of cases, dry firing is an acceptable way to empty the reservoir. However there are a few models that may be damaged by doing so. See if the manufacturer addresses it in the manual or post here with the models to see if we can help.

There are a number of other ways to do it that don’t pose a risk of damage, and may be more convenient too. But again, it varies by model so it’s best to ask. 

 

[scotton]

Some models, like the Marauder, have a pin that screws into the hammer adjustment hole at the back to degas the gun. Other guns have similar degassing methods. The Avenger degasses by turning a set screw next to the regulator adjustment screw.

The most basic way to degas a gun that doesn't have a legit method is to slowly unscrew the air gauge until air starts leaking out. The problem with this method is it can cause swift and early failure of the o-ring on the gauge (because the high pressure air pushes it out. I would probably use the dry fire method before the gauge method, depending on the gun.

Every gun should have a proper method for degassing, you will have to look it up for each particular gun.

 

[Elgreco]

Thanks! That confirms my understanding. The rifle I was talking about is a Hatsan Factor RC and from briefly glancing on the manual available online I believe it mentions a bleed valve of a sorts to safely relieve pressure from the tank. 

That's the only one I am planning on playing with the settings. The other two I am planning on leaving set as they came from the previous user as they have made all the legwork for me and at the most play with hammer settings.

 

[biohazardman]

You are correct as nervoustrig points out. and scotton has good info also. I always loosen the gauge to let the pressure bleed off myself and have never had a problem with seals on my gauges as they are not o-rings but a hard Delrin or PTFE type material that is not harmed by the pressure release.

 

[nervoustrig]

True, backing off the gauge until it starts hissing is usually fine so long as we are talking about a gauge with parallel threads and a separate seal. However I’m not a fan of doing it with tapered threads (easily distinguished by the presence of PTFE tape on the threads) because it’s reducing radial thread engagement. Even when done safely, it seems to increase the odds of leaking if all you do is retighten it when done. 

Regardless, if you are dealing with a regulated rifle, be sure your approach gets the plenum (regulated, low-pressure side) evacuated. For example, some models have only a single gauge on the reservoir (high-pressure side). If you evacuate that side, the plenum is still pressurized and potentially dangerous.

 

[biohazardman]

Once again I would have to agree with nervoustrig I had not thought about the tapered threads as I do not have guns with any. Also loosening the correct gauge is very important as well.

 

[Elgreco]

Apparently with the Factor RC the tank us removable under pressure ( good cause I won't have empty the whole tank) and there is a valve release the remaining air in the plenum. Unfortunately the manual doesn't illustrate the valve so I guess I will have to wait for the rifle to see how that looks like. 

 

[Odoyle]

I would shoot least 500 rounds break in b4 adjusting anything.

 

[UncleHoot]

Bleed air SLOWLY because a fast discharge causes condensation of any moisture in your tube/bottle.



Kindly 'Ol Uncle Hoot