yes, most of the time it fix the low 1st shot after long ideal. HS my settle the next day and my have to tighten the HS a tad.
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First shot lower fps on regulated pcp
- Thread starter hvack
- Start date
Not true . Never said ONLY first shot... The first shot was slow !!! Ernest look at this .... lol It's not masking anything ,,, if you read all the post's, it now always shoots consistent , there for nothing masked .....
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your right you have to synchronize the reg pressure and HST to get the best consistency. do you have a reg tester to check for creep????
we are talking about the 1st shot being low after long ideal, not a full string.
while tuning---->that's on my check list, if it doesn't shoot within the ES the 1st shot the next morning it doesn't get ship out.
That's a bitch-----> you have to shoot off a round every time you want to shoot every morning or knowing it going to shoot slow after 2 hours waiting for game!!
edit: yes I have read the 1st post, it don't matter, some time it takes 5 shots to gradually creep back to normal speed,
we are talking about the 1st shot being low after long ideal, not a full string.
while tuning---->that's on my check list, if it doesn't shoot within the ES the 1st shot the next morning it doesn't get ship out.
That's a bitch-----> you have to shoot off a round every time you want to shoot every morning or knowing it going to shoot slow after 2 hours waiting for game!!
edit: yes I have read the 1st post, it don't matter, some time it takes 5 shots to gradually creep back to normal speed,
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Had fun getting my Colibri to shoot right! Sounds similar to what the op was experiencing.
Being sub 12FPE here I'd set the hammer to give 11.5FPE
If I left my gun for a while the first shot would be 9FPE then 10 then 11 and roughly consistent here for the rest of the mag.
I finally got it sorted today but had to remove one of the Belleville washers and set the regulator really low. Now if I pick the gun up it'll be consistent from the 1st shot. I shot some wicked groups today! Never been able to before as it'd climb the target card usually!
It is really consistent at 23FPE so I'm told, just a shame we can't do that here without FAC
Being sub 12FPE here I'd set the hammer to give 11.5FPE
If I left my gun for a while the first shot would be 9FPE then 10 then 11 and roughly consistent here for the rest of the mag.
I finally got it sorted today but had to remove one of the Belleville washers and set the regulator really low. Now if I pick the gun up it'll be consistent from the 1st shot. I shot some wicked groups today! Never been able to before as it'd climb the target card usually!
It is really consistent at 23FPE so I'm told, just a shame we can't do that here without FAC
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Trying to get my head around the idea that the hammer spring adjustment somehow effects the shot consistency "changing" from shot 1 to 100. Originally the OP's gun was shooting pretty consistent (w/i 2% ES), with the exception of the first 2 shots (7% low) , during the entire fill, right? Now by bumping up the hammer spring ALL of the shots are 1%, even the first 2.
What would be the "reasoning" that with a lighter adjusted hammer spring it "sometimes takes 5 shots to gradually creep (funny you picked that word) back to nomal speed" versus the consistency right from the beginning with a heavier hammer spring? What is "causing" the first 2 shots to be the only ones not consistent? Sure not the HS, right? If so, then how?
I do agree that if you have the gun tuned right on the knee of the velocity (max pressure as you refer to it) that the string will be more consistent over the entire string vs a tune where you are lower on the curve, but this will also be during the ENTIRE string, not just shots 3 thru the end........unless there is an issue where the pressure in the plenum is changing while the gun is sitting (problem with regulator). I also know that if the tune the gun past the curve, (ie hammer spring set for a pressure above the regulator set point) this will not happen as the hammer spring can still overcome the raise in pressure. The downside to this is that you will not see there is a problem and you will also be wasting air. (Lower efficiency)
It's kinda neat how I found out that it was my regulator creeping. The gun in question has a Ninja bottle with a tank gauge. I have an on/off valve between bottle and gun with a gauge. When the gun was sitting (filled to 3K) I could see the 1500PSI on the "regulated" air. The gun shot fine. After letting the gun sit a couple days I would notice when I picked it up that the "regulated" gauge was over the 1500PSI mark. Shot the gun and it would return to the mark. When I saw this happening I checked it on the chrony and noticed that my first shot was always much lower then the rest. I decided I could either fire a shot before I start for the day, or I could find out what the problem was. Did some research and determined that it looked like the regulator was "creeping". Sure enough I took the regulator apart, flipped the Delrin ball in the regulator (which I noticed had a deep "gouge" embedded from the seat) and I've since not had any raise in the regulated pressure while the gun is sitting. The shots are ALL w/i 1.5%.
My guess is that the OP's regulator is still creeping. The regulator will continue to creep over time and it will eventually get worse. After longer periods of time sitting the guns pressure will slowly rise and the OP's will see that his problem will eventually return (if he keeps checking the velocity over the chrony). The gun will get to the point where he has to get someone to check it and they will tell him that the regulator has stopped regulating. How long with the take? Who knows. Like Kris said - As long as he is happy shooting it all's well.
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All this article makes me think is that we may need electronic regulators for our pcp's so they can be close at first, or adjust on the fly for different conditions ... To any pressure ...
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I'm old school, so I prefer mechanical I can fine tune them in great detail at will.
but Electronic are vary limited in there intended signed, you have to be a E-engineer or software writer just to modify them or make new electric parts/circuit board etc. limited in fluxing --- limited in selections.
mechancal you can always make parts with a lathe and a mill - make tools to test them Or even with a fine file.
but Electronic are vary limited in there intended signed, you have to be a E-engineer or software writer just to modify them or make new electric parts/circuit board etc. limited in fluxing --- limited in selections.
mechancal you can always make parts with a lathe and a mill - make tools to test them Or even with a fine file.
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They could give the user a completely open source tool that allows all adjusting possibilities from your laptop ...
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Reading all of this, makes me wonder how does it work when it comes to FX impact ? since the power knob controls the hammer spring tension. And add to it the valve opening. lots and lots of possibilities and calculations.
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I am unable to measure the 'pressure', what I can comment on is the effect on fps.
My 12fpe Air Arms S400 had the typical unreg'd increase in fps before decay. After some fettlng (tuning?) the 'sweet spot' was about 35 shots (a pressure spread of about 70bar) with an ES of 10-12 fps.
After installing a regulator and balancing the reg pressure, firing pin spring and hammer spring I consistently get an ES of 3 fps from first shot to 70th/72nd shot. If I am experiencing an over/under pressure from the reg after adding some more air it is not revealed in the fps.
A thought, mechanically a reg'd gun will still have a 'sweet spot', by having a reg we are managing the pressure parameter to achieve a tighter and extended 'sweet spot' - if you shoot past the reg set point you will experience fps decay i.e. the pressure is no longer being managed so we move out of the 'sweet spot'. Could it be the 'balancing' I have done has ensured any over/under pressure after adding some more air is still within the range of the 'sweet spot'?
My 12fpe Air Arms S400 had the typical unreg'd increase in fps before decay. After some fettlng (tuning?) the 'sweet spot' was about 35 shots (a pressure spread of about 70bar) with an ES of 10-12 fps.
After installing a regulator and balancing the reg pressure, firing pin spring and hammer spring I consistently get an ES of 3 fps from first shot to 70th/72nd shot. If I am experiencing an over/under pressure from the reg after adding some more air it is not revealed in the fps.
A thought, mechanically a reg'd gun will still have a 'sweet spot', by having a reg we are managing the pressure parameter to achieve a tighter and extended 'sweet spot' - if you shoot past the reg set point you will experience fps decay i.e. the pressure is no longer being managed so we move out of the 'sweet spot'. Could it be the 'balancing' I have done has ensured any over/under pressure after adding some more air is still within the range of the 'sweet spot'?
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I'm still Unsure of exactly what was happening with my bobcat, After hundreds of chrony testing and a adjustment of just the hammer spring , I am getting consistant shots from 1 to 60 all around 855-865 with.25 mkII heavey's . I think the spring got weaker after 7500+ rounds and settled to weak for the 140 bar reg setting then I turned up the spring and now no more low fps on first shot ever, not high either and this has been over hundreds of shots and setting for days and shooting fast , slow ect.....
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Wasn't saying anything about power... I am the origanal op. I was trying to stay on topic with the first post. LOL Its about how the reg is not leaking through causing the first shot to be low..
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Actually this is likely EXACTLY what was happening. You upped the hammer strength so that now it doesn't show. Might not have done a real scientific test for it, but you likely lost efficiency.
Figure it this way. If your reg is set for 100bar and the hammer is set to be right on the "edge" of the curve, when the pressure creeps up to 110bar you will see a drop in velocity.
If you set the reg for 100 bar and then up the spring to where it would be right on the "edge" of the curve for 110bar you will not see a drop in velocity when the regulator creeps up to 110, you would only see it if it were to creep beyond 110.
Result? you will be using more air then you would if tuned right on the "edge" at 100 bar.
If you don't want to accept this "explanation" you can always chalk it up to the "UN-explained".
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Why would the pressure creep up to a point and stop if there is a leak around the reg... if I have 250 bar in the tank it should creep up to that and even with the hammer spring harder it would still be low on the first shot , unless you are thinking that the reg has a new setpoint...
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Reg creep is not a leak around the reg, that air would just go out the vent hole and lower the overall tank pressure on the gun gauge. I lost 10 bar in 8 hours from a nick in the outer reg o- ring on the 500 Royale. Reg creep is when you are shooting a string over the chrony and the reg settles on a number after each shot- say 150 bar. Your gun's main valve is tuned for 150 and as you sleep, your unadjusted regulator goes slowly up to 165 bar (creep). Now that first shot is slow because of the valve timing in relation to pressure. Unregulated guns usually shoot slow at higher fills, then higher speed at optimal, then slower at lower.-- the bell curve. Your crept reg is too high and the shot is a victim of too much pressure for the hammer spring/valve. If your reg is too low, then an air leak outside the gun would be evident.
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That sucks cause that gun did it from day one when I got it new from AoA.....So that is why I thought it was just a miss adjusted hammer spring from the factory .
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No.... Misadjusted regulator from the factory. My Fx regulator is Impossible to adjust --- I am on attempt #78 with my homemade reg tester. Hope to make a post soon. One hair twitch too far with the wrench and either creep or low reg pressure results.
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This is "kinda" what happens. The regulator seat gets "indented" which causes the regulator to open just a tad bit farther, causing just a bit more pressure. This is what causes the slight pressure increase.
My guess is that it will slowly get worse and worse until you have to "fix" it, with something other then hammer preload. How long it will take? Who knows? It will eventually get to the point where the regulator does not regulate at all. That's when you know it's gone bad.
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