Relationship between regulator and spring

[Wokdaf]

Let me preface this by saying the spring is NOT adjustable outside of cutting or adding spacers and the regulator is NOT externally adjustable and thus I have to completely degas whether going up or down pressure wise. Incremental adjustments of both just isn't in the cards.

So the question is, what IS the relationship between the hammer spring and regulator? For example, if hammer is too light for regulator pressure, what would expect the fps to be start/middle/end of shot string. If the hammer is too heavy for the reg pressure, what would expect the fps to be start/middle/end of shot string. Ideally you'd want to get consistent shots across till it drops off the reg. As it is, my fps are still on a bell curve, not drastic, but bell curve nonetheless. I'm trying to flatten that bell curve as best I can. I'm about 4 months into PCP and this is all still very new to me.

 

[orangeokie]

I'm a novice to PCPs, like you, but with my reading on the subject over the past few months there is a sweet spot for spring "strength" as it propels the hammer. Too light of spring tension reduces hammer speed/force and thus the amount of air released for the shot, hence projectile speed (measured in FPS) goes down. Conversely, excess hammer force releases maximum air pressure resulting in maximum projectile speed but can also result in wasting air through "double tapping" the valve. BTW, which regulator does not allow you to adjust upward without first de-gassing? Just curious.

 

[Emu]

There are to forces in fight: the one of the spring and the one of the pressure the regulator allows to get into the chamber.

There is an equilibrium point in which forces are perfect to get the maximum of fps. Less or more pressure implies less fps.

Then in a valve open with a hammer pushed by a spring more preasure after some point will not allow the valve to open enough and less fps will be obtained.

In the lower side, less pressure and more force in the hammer spring will not provide more fps.

On other systems of firing like the Houben K1, the LCS, the Rattler and the Sidewinder more pressure and more counter clockwise turns to open more the flow of air implies more fps. But that applies just for that kind of rifles.

In order to get to know what is the perfect sweet spot for your rifle without dissasamble it you should: shoot Your rifle at 200 bar and then measure fps, then at 180 bar and meassure fps, then at 170 and measure fps, and so on until you get the highest measure of fps before start to dramatically decrease.

If you noticed that first you had, for example 910 fps at 200 bar and got 980 fps at 110 bar, then you need to dissasamble the rifle, take the regulator, measure the total length and then screw the central adjuster to make the regulator a little shorter (making it to reduce the pressure it allows to pass to the chamber).

 

[Wokdaf]

There are to forces in fight: the one of the spring and the one of the pressure the regulator allows to get into the chamber.

There is an equilibrium point in which forces are perfect to get the maximum of fps. Less or more pressure implies less fps.

Then in a valve open with a hammer pushed by a spring more preasure after some point will not allow the valve to open enough and less fps will be obtained.

In the lower side, less pressure and more force in the hammer spring will not provide more fps.

My overall question was to try to understand why, with a regulator, do I have a bell curve for this gun. I don’t have it for my other gun granted that gun it’s externally adjustable for both hammer and regulator.

So I understand why a bell curve happens with an unregulated gun. There is more pressure for hammer to deal with at first so lower fps as it’s harder to push valve. Then the more shots, pressure decreases so hammer is able to push valve further resulting in fps increases until pressure just gets too low causing Fps to go lower again, ie bell curve.

Why would I see this in a regulated gun? Transfer port opened too big? Reg set too high? Hammer?

 

[Wokdaf]

I'm a novice to PCPs, like you, but with my reading on the subject over the past few months there is a sweet spot for spring "strength" as it propels the hammer. Too light of spring tension reduces hammer speed/force and thus the amount of air released for the shot, hence projectile speed (measured in FPS) goes down. Conversely, excess hammer force releases maximum air pressure resulting in maximum projectile speed but can also result in wasting air through "double tapping" the valve. BTW, which regulator does not allow you to adjust upward without first de-gassing? Just curious.

It’s the aea challenger standard. Yeah it sucks that u have to degas it…and I don’t have my compressor yet. So there’s A LOT of reluctance to adjust it lol

 

[Emu]

My overall question was to try to understand why, with a regulator, do I have a bell curve for this gun. I don’t have it for my other gun granted that gun it’s externally adjustable for both hammer and regulator.

So I understand why a bell curve happens with an unregulated gun. There is more pressure for hammer to deal with at first so lower fps as it’s harder to push valve. Then the more shots, pressure decreases so hammer is able to push valve further resulting in fps increases until pressure just gets too low causing Fps to go lower again, ie bell curve.

Why would I see this in a regulated gun? Transfer port opened too big? Reg set too high? Hammer?

Regulator set to high (normally). More pressure do not allow the valve to open correctly until you get to the “sweet spot” and then you start to hit high because you get then more fps.

 

[Wokdaf]

Regulator set to high (normally). More pressure do not allow the valve to open correctly until you get to the “sweet spot” and then you start to hit high because you get then more fps.

That’s what I was thinking too, but then the pressure is supposed to be the same until it drops off the reg, unlike non-regulated air? Do that shouldn’t be the case right?

 

[Emu]

That’s what I was thinking too, but then the pressure is supposed to be the same until it drops off the reg, unlike non-regulated air? Do that shouldn’t be the case right?

If the sweet spot is lower that the regulated preassure then the rifle will shoot better once is below the preassure of regulator.

 

[bunkeru2k]

It makes more sense if you picture how your valve operates. You have a spring that drives the hammer and a spring behind the valve that lets it open and then returns it closed after the hammer strikes it. When those two spring strengths are roughly in balance, the gun behaves normally. If one or the other is much stronger than the other, then you get velocities that are at the very bottom of the curve.

Now lets take it one small step forward and look at air pressure. The air pressure behind the valve IS the spring. The actual metal spring in there does nothing really but keep the valve closed at very low pressures.....once that air pressure starts getting anywhere close to being able to fire, it is the only force behind the valve doing anything. It does not act like a normal spring though.....it is much more comparable to a shock on your car. You want the strike to be absorbed "gradually" until it hits the peak spot and then it will rebound in a smooth manner. If the hammer strike is very light, then the valve opens very briefly and not as far as a proper strike. On the other hand, if you smash it with too much force it will hammer open and closed quickly and also will give you lower velocity.

As to specifics for what velocities and such, that is impossible to say.

 

[DesertSilver]

I'd be willing to bet it's set way to high and it's no longer regulating the pressure. I had that happen on my liberty. You set your reg to the pressure you want. Then you increase the hammer spring preload until it stops increasing fps then back it off around 10% of the peak muzzle velocity. That should put you at the most efficient setting.

 

[Wokdaf]

I'd be willing to bet it's set way to high and it's no longer regulating the pressure. I had that happen on my liberty. You set your reg to the pressure you want. Then you increase the hammer spring preload until it stops increasing fps then back it off around 10% of the peak muzzle velocity. That should put you at the most efficient setting.

That’s the downside of this gun in that the hammer spring is light…or it’s heavy. 2 settings and that’s it.

 

[weevil]

Higher reg pressures require more hammer. If your reg pressure is set to high for the hammer strength (let’s say 150 bar) then you’ll get a flat string until your bottle pressure drops below 150. Then you’ll get increasing speed until you hit the reg pressure thats optimum for your hammer (say 130) then speed will drop with more shots. Best thing to do is start at low reg pressure and shoot a string, then repeat with a little higher pressure. When you see the bell curve emerge, step back to the previous reg pressure and that will be (thereabouts) your sweet spot.

 

[Wokdaf]

Higher reg pressures require more hammer. If your reg pressure is set to high for the hammer strength (let’s say 150 bar) then you’ll get a flat string until your bottle pressure drops below 150. Then you’ll get increasing speed until you hit the reg pressure thats optimum for your hammer (say 130) then speed will drop with more shots. Best thing to do is start at low reg pressure and shoot a string, then repeat with a little higher pressure. When you see the bell curve emerge, step back to the previous reg pressure and that will be (thereabouts) your sweet spot.

Thank you. That’s what I’m looking for, relationship/cause and and effect of one being higher or lower than the other.

 

[UCChris]

If your hammer spring is too light for the reg pressure, your ES and SD will be larger than if the reg pressure and hammer spring are well balanced. I know degassing sucks, but I would start with a pretty standard pressure for your given caliber and power level. If the ES is wider than you think it ought to be, decrease the reg pressure by 10 bar or shim the hammer spring and see if it tightens up.

If your hammer spring is too strong for the reg pressure, ES and SD will be pretty good, but the velocity will drop like a rock as soon as it goes off the reg.

 

[Wokdaf]

If your hammer spring is too light for the reg pressure, your ES and SD will be larger than if the reg pressure and hammer spring are well balanced. I know degassing sucks, but I would start with a pretty standard pressure for your given caliber and power level. If the ES is wider than you think it ought to be, decrease the reg pressure by 10 bar or shim the hammer spring and see if it tightens up.

If your hammer spring is too strong for the reg pressure, ES and SD will be pretty good, but the velocity will drop like a rock as soon as it goes off the reg.

U know if it was for the power this gun offers, I wouldn’t have bought it as there’s no reg gauge so all u can do is shoot it till it drops off the reg to figure out your reg setting. Jo hammer adjustment outside of swapping out spring.