one possibility is that the plenum in your regulator is filling slower than you are shooting. I’m guessing there’s a longer delay when you switch out magazines and that allows the regulator to pressurize more fully. That would explain the jump each time you start a new magazine but not why is steadily decreasing Have you tried taking shots with longer delays in between them just to see what happens there? Like try waiting 30 to 60 seconds between shots.
I'll gladly listen to anything else anyone has to chime in, but I've started the return process based on Pasadena Mike saying the shot string should be mostly linear
Mike, when shooting shot strings in the future, how long should I wait to let the plenum recharge between shots? is five seconds between shots long enough?
And one last question.. if I let the gun sit for a few minutes, and the first shot I fire is significantly faster than what the gun was shooting during my shot string, is this 'reg creep'? Is there an acceptable amount of this I should expect? Or if my gun was shooting velocity X during the shot string, should I expect it to fire the same velocity even after sitting for several minutes?
Being a new regulator, some amount of pressure creep is expected. Give it some time to break in…the seal on the end of the regulator piston will develop an impression of the valve seat and the pressure creep should all but go away. To know if it’s getting better over time, fire a couple of shots and make a note of the pressure as it reads immediately, then again after 1 min, 5 minutes, and an hour. Then use it for a few days and record the pressures again. Also you will want to get the hammer spring tension (HST) dialed in optimally. Right now the fast first shot indicates too much HST which is wasting air and contributing to velocity fluctuations. To do that, back off the adjuster until the velocity falls to somewhere around 95 – 97% of the current maximum. FWIW my .22 cal did not have enough adjustment range for a 1700psi setpoint. Even with the adjuster backed all the way out, the velocity would not come down so I removed the spring and cut off one coil. That did the trick. The good news is the spring is easy to remove if you need to. Use a rotary tool with an emery wheel to cut it. Note also you’ll want to tweak the HST after it has broken in because the setpoint will have shifted up somewhat as the seat breaks in.
Quote from: nervoustrigger on August 01, 2022, 02:42:28 PMBeing a new regulator, some amount of pressure creep is expected. Give it some time to break in…the seal on the end of the regulator piston will develop an impression of the valve seat and the pressure creep should all but go away. To know if it’s getting better over time, fire a couple of shots and make a note of the pressure as it reads immediately, then again after 1 min, 5 minutes, and an hour. Then use it for a few days and record the pressures again. Also you will want to get the hammer spring tension (HST) dialed in optimally. Right now the fast first shot indicates too much HST which is wasting air and contributing to velocity fluctuations. To do that, back off the adjuster until the velocity falls to somewhere around 95 – 97% of the current maximum. FWIW my .22 cal did not have enough adjustment range for a 1700psi setpoint. Even with the adjuster backed all the way out, the velocity would not come down so I removed the spring and cut off one coil. That did the trick. The good news is the spring is easy to remove if you need to. Use a rotary tool with an emery wheel to cut it. Note also you’ll want to tweak the HST after it has broken in because the setpoint will have shifted up somewhat as the seat breaks in.I intended to reduce the HS until velocity drops to 95-97% of maximum, but it seemed like a moving target with the velocity dropping on its own with each shot. I should add I have almost 500 pellets through it as I shot it a lot before I got the chronograph. At first I thought it was the cheap pic rail causing POI shifts. Eventually I started to suspect the regulator, and I managed to bag several ground squirrels by just keeping it topped off. I've lost all interest in shooting it now after looking at the chronograph readings. I encountered the same hot first shot of the mag phenomena with the gun set to 1400psi reading with 1.5 turns out on the HS as well.When I receive my replacement, I will try to keep breaking it in with a hot first shot of the mag, as long as my shot string is otherwise linear. Is there any 'new regulator' explanation for the digressive curve?
Quote from: princecolby on August 01, 2022, 03:21:42 PMQuote from: nervoustrigger on August 01, 2022, 02:42:28 PMBeing a new regulator, some amount of pressure creep is expected. Give it some time to break in…the seal on the end of the regulator piston will develop an impression of the valve seat and the pressure creep should all but go away. To know if it’s getting better over time, fire a couple of shots and make a note of the pressure as it reads immediately, then again after 1 min, 5 minutes, and an hour. Then use it for a few days and record the pressures again. Also you will want to get the hammer spring tension (HST) dialed in optimally. Right now the fast first shot indicates too much HST which is wasting air and contributing to velocity fluctuations. To do that, back off the adjuster until the velocity falls to somewhere around 95 – 97% of the current maximum. FWIW my .22 cal did not have enough adjustment range for a 1700psi setpoint. Even with the adjuster backed all the way out, the velocity would not come down so I removed the spring and cut off one coil. That did the trick. The good news is the spring is easy to remove if you need to. Use a rotary tool with an emery wheel to cut it. Note also you’ll want to tweak the HST after it has broken in because the setpoint will have shifted up somewhat as the seat breaks in.I intended to reduce the HS until velocity drops to 95-97% of maximum, but it seemed like a moving target with the velocity dropping on its own with each shot. I should add I have almost 500 pellets through it as I shot it a lot before I got the chronograph. At first I thought it was the cheap pic rail causing POI shifts. Eventually I started to suspect the regulator, and I managed to bag several ground squirrels by just keeping it topped off. I've lost all interest in shooting it now after looking at the chronograph readings. I encountered the same hot first shot of the mag phenomena with the gun set to 1400psi reading with 1.5 turns out on the HS as well.When I receive my replacement, I will try to keep breaking it in with a hot first shot of the mag, as long as my shot string is otherwise linear. Is there any 'new regulator' explanation for the digressive curve?Lol I was wondering what the piece of paper looking thing was on the table until i zoomed closer lol. Love it. I live in SoCal and ground squirrels are my favorite game.
This is my first PCP. As soon as I got it, I degassed it, closed the regulator, then backed it out 1/8 of a turn. When I filled it up, the regulator was at like 2900 PSI. so I degassed, closed the reg, filled the gun, then slowly turned the regulator in infinitesimal little turns, dry firing to settle the reg, and continuing until I got to 1400 PSI. I turned the hammer spring 1.5 turns out. I was trying for Steve from AEAC's 'eco tune' which he says he got over 100 shots at 25fpe....
Quote from: princecolby on August 01, 2022, 12:47:07 PMThis is my first PCP. As soon as I got it, I degassed it, closed the regulator, then backed it out 1/8 of a turn. When I filled it up, the regulator was at like 2900 PSI. so I degassed, closed the reg, filled the gun, then slowly turned the regulator in infinitesimal little turns, dry firing to settle the reg, and continuing until I got to 1400 PSI. I turned the hammer spring 1.5 turns out. I was trying for Steve from AEAC's 'eco tune' which he says he got over 100 shots at 25fpe....When you closed the regulator, did you turn it clockwise or counterclockwise? When degassed it should be turned clockwise until it stops, and counterclockwise turns will increase the regulated pressure. 2900 psi at 1/8 of a turn sounds like it was all the way opened CCW to max pressure when the gun was pressurized, then gradually lowered clockwise. Unfortunately, if so the regulator may no longer be working properly.