Is This What Is Meant By "Regulator Creep?"

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Jason, my gun holds pressure shown on the factory FX gage no problem. It’s only after the first shot and second shot after a wait of up to 2 minutes. If I keep cocking and shooting non stop, velocities are good and ES is low. It’s when I stop to fill a magazine or kick back for a few minutes is when the first shot is way dropped. So, the air that’s stored after the reg is leaking(plenum side). Chuck called it for sure.
 
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Okay thanks for the extra detail but unfortunately I'm not understanding. For example, "post reg" _is_ the plenum. If it leaks there, the valve seat will continue to allow a slow flow of air from the high pressure side to keep the plenum topped off. And if the valve seat is prone to creep, the plenum pressure will actually rise a bit and the first shot or two will be slower. It may be that there isn't sufficient resolution on the output gauge to discern that it is climbing slightly.

BTW, do you have the HST adjusted to about 97% of peak velocity?
 
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Yes on the 97- 95% of peak velocity, Nervous.



I cant say that the reg is trying to refill that plenum, as I haven’t tried testing for that. At one time I had all four of my magazines filled with pellets, so popping off a used up one and a new one popped in, no change in velocity. If I stopped, put the gun down and say, loaded up two magazines and polled one in to fire, there will be a drop in velocity. 



The gun held 190 BAR for two days, as I made a note on the air pressure when I put away the gun
 
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A couple posts back, It sounds like you found the leak with bubbles, was this not the problem ? Sounds now like it still creeps.
Click to expand...

I found the leak a few hours ago and posted my findings, but have not drained the gun of air and fixed it yet. I have a full house due to it being my kids birthday, so it’ll be a couple of days till I actually fix it. 

Am confident I will NOT have any low velocity first shots anymore, and I am confident I’ll be at 927-930 average velocity. No creep for me
 
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Hi. I'm experiencing the exact same thing with both of my FX Wildcats, one in cal. .177 and the other in cal. .25 and I can't figure out what the heck is going on. Very frustrating. The air comming from the regulator is just short of 140 bars on both rifles, and will creep up 2-3 bars over a couple of hours. And no more creep after that. I've mounted a digital pressure regulator on the bleed valve, and the pressure from the regulator is stable at ~138 bars a second after a shoot, no matter if there is 2 seconds after the previous shoot, or 30 minutes after the previous shoot. The pressure from the regulator stabilize fast and the creep isn't worse than I can live fine with it. I have relubed the regulator and the receiver several times, I have tried both silicone oil, silicone grease and dow 33 grease. I have gone over the mechanic parts looking for bindings, but there is no bindings, everything is smooth and free. Anyway, when I reload the magazine and the rifles have rested for a minute or so, the 3-4 first shots are low in speed, then the remaining pellets will shot at the same speed. Put in a new loaded magazine and keep on shooting immediately, and there's no low shoots. If I have to reload a magazine and the rifle is resting for a little while, 3-4 low speed shots... There's obviously something I'm overlooking here, but I'm not able to understand what. Very strange and very frustrating. 😫
 
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FYI, lubrication will almost never help with creep. The axial forces compressing the Belleville spring washers is vastly higher than any conceivable friction.

Get a 5x or 10x loupe and inspect the valve seat. Where the surfaces come together, they need to be smooth so they will mate cleanly. Any scratches, dents, or machining marks will permit air to continue to slowly seep through until the pressure eventually rises enough to sufficiently squeeze and deform the soft side and finally halt the transfer of air.

Case in point, just today I received a cheapie paintball regulator to try out. I put it in my test jig and the pressure would come up to 700psi and then creep up to 825psi over a period of a few minutes. I took it apart and sure enough, the plastic side of the valve seat had a series of concentric machining marks from where it was cut in a lathe. I used some 400->600->1200->2000 wet/dry sandpaper to dress the surface smooth:



Now it comes up to the setpoint straight away and stabilizes. Five minute fix.
 
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FYI, lubrication will almost never help with creep. The axial forces compressing the Belleville spring washers is vastly higher than any conceivable friction.
Click to expand...

I know, but just to rule out the possibility of a "hanging" piston in the regulator I relubed to be on the safe side. I also put the piston in the lathe and did a finnishing cut of the valve seat on one of the rifles, but they both behaves similarly so I think the regulator is not the problem. But I can do it again just to be sure. 
 
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As already mentioned, reg creep is a very slow leak on the reg sealing face that allows air to pass making pressure rise until it gets to a point where the increased pressure has enough force the crush the sealing face tighter slowing then stopping the leak ( like really twisting a leaking tap to stop a drip) 

there is another factor that can cause the reg pressure to rise, temperature! When the gun is fired, the air decompresses and get cool, successive shots keep the plenum chamber cool, however, allow the gun to sit for a while and the plenum will warm, pressure will rise giving the impression that the reg is leaking, it may not be! Larger plenum volume will give a greater rise in pressure due to temperature. I have a reg tester that I use to adjust reg pressure, if I set the reg to say 100 bar, then tap the knock valve a few times to simulate shots, the reg pressure will still indicate 100 bar, leave it for an hour and it will climb to 110, even if I have disconnected the air supply.

If the reg is leaking and the stored pressure does rise then the first shot will most likely be slightly under power as there is more pressure holding the valve shut making it harder for the hammer to open the valve. I would be surprised if the second shot would also be erratic as unless there was a complete reg failure.

there are several other reasons why the first few shots are erratic that have nothing to do with reg creep. The sealing face of the firing valveis under considerable force, this pressure slight deforms the shape of the valve stem sealing face causing to stick to the valve front port. This sticking may take 1/2 a dozen or so shots to sort out. Valves with a sharp edge on the vp are more prone to this than a vp with a slight radius.

Depending on the design of the hammer and spring assembly, there is the possibility that some of the parts also stick for a few shots.

Another cause could be reg material, although delrin is a very good to make a sealing face, it is temperature sensitive and slightly elastic, not the best thing to use for the piston of the reg, fx regs are made from delrin, IMO a better option would be a steel or brass reg piston with a delrin core as illustrated in the picture above. This could explain why the installation of a huma reg cures a lot of reg related issues.



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