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Tuning Question for you Prophet experts out there

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MikeVV

MikeVV

Member
Jan 10, 2019
3,545
2,231
SoCal, United States
I pulled my Prophet Compact out today to do some shooting, and found that it's been leaking air.

It's only about 3 months old, but I really don't want to send it back to the dealer, when I should be able to do the maintenance myself. After all, I build my own cars and bikes,, built space craft (have "#2" sized screws !) for over 20 years, I should be able to do this....right ?

Anyway, it "seems" that it's leak may be in the regulator. I say this because both the cylinder pressure AND the regulator pressure drop at the same time. Would this be a correct assumption ? And now that I finally bought a chronograph, in adjusting it today...or rather "trying" to adjust it today, I was chasing the regulator pressure at every trigger pull. It seemed to like stopping at about 100 bar and shoot fine from there (no matter where the hammer spring is adjusted to). Raise it to 120 bar, after two shots, it's back to 100 bar. Two more shots, it's still at 100 bar.

Forgot to mention. In this pressure chase, the chronograph indicated that the pellet was moving in accordance with the hammer spring pressure AND the regulator pressure. One OR the other drops, the pellet speed drops.

If I've given enough information, what might be my steps in finding the problem...without making it worse !?

Thanks for any help.

Mike
 
What caliber Mike? 

For the leak, have you tried soapy water? Check with the soapy water and spray on the gauges too.

You said with the pressure at 100 bars really doesn't matter the HS adjustments, this match my experience with .25 caliber, that's why my first question was what caliber. 

I've come to the conclusion this gun, at least mine, likes higher reg pressure, the spring and weight mine came was designed for 150 bars. I was trying to run a low regulator tune and my results are the same you are describing. For me to be able to go low I'll need to change the spring too but I haven't been able to find were to order it.

My advice is to start your tune with 150 bar and going down, as a reference, I ended up with a pressure of 130 and I was able to find the right HST for that pressure, lower than that and the speed start going all over the place.

The other issue you are describing seems to be related to regulator recovery time. You said that after the regulator is at 120 then couple of shots and the regulator goes to 100, for how long?

My suggestion here is same as before, set the regulator at 150 first, and test.

One more question Mike, the gun is rated for 300 bars, at what pressure you are filling? With a brand new gun, at least while the regulator is breaking in, I'll recommend filling to 250 max until everything settle in.

Hope this helps.
 
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Before you get out the tools, this is what I would do. Turn the reg up to 130b. Have at least 250b in the tank and shoot the gun for a bit. See if it’s ok then. All regs, whether it’s an AMP, Huma or Ninja have an operating range. If you are trying to operate at the extreme ends of these ranges you could be going into the bypass mode. Bypass mode is essentially shooting the gun unregulated.
 
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Sorry, it's a .22 Compact.

I'm gonna look into some leak detector fluid. We used it a lot when I was working (Aerospace).

I checked this morning, no "visible" gauge pressure changes. On the regulator pressure, when I received my full sized Prophet Performance, it was "tuned" by the dealer and the regulator pressure was only 80 bar ! All was / is well with that gun. Though I did turn it up to 100 bar, and play with the hammer with the chronograph attached. Seems to like the new settings. Even a little quieter, shooting 915 fps (aver.) 18.3gr .

That's when I set up the Compact to test. I noticed right away that the cylinder and regulator pressure was much lower than during it's last use, about two weeks ago. I filled it to 210 bar, the gauge pressure came up fine, no obvious leaks. That's when the problem arose.

I'll give what Vetmx suggests, and see what happens.

Will let you know tomorrow.

Thanks all.



Mike
 
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A quick test -

Filled the gun to 230 bar (no more available pressure) ! Adjusted the regulator to 130. The first shot, the needle dropped to 110 bar. Five more shots, the needle crept up to 120 bar, and stayed there for the rest of the full magazine.

The adjustment screw, hex head, located BETWEEN the 'set' regulator gauge and reservoir gauge MAY need to be adjusted slightly. That hex head is on the topside of the gun and pointing at the underside of the shroud.

I have the RTI PPC in .22

Ask Rob.
Click to expand...

What does this hex screw do ? 

Don't want to mess with things that I don't know what they are for. That's one reason that's I'm HERE, asking you guys the questions. I like details, not just "do this" when you are messing with things that I don't know what they do.



NOTE - I also need to let it sit for about two weeks like the last sit, period to see it it leaks down like it did. I'll put another magazine thru it, refill it, and put it away, to see what happens.



Mike
 
Upvote 0
A quick test -

Filled the gun to 230 bar (no more available pressure) ! Adjusted the regulator to 130. The first shot, the needle dropped to 110 bar. Five more shots, the needle crept up to 120 bar, and stayed there for the rest of the full magazine.

The adjustment screw, hex head, located BETWEEN the 'set' regulator gauge and reservoir gauge MAY need to be adjusted slightly. That hex head is on the topside of the gun and pointing at the underside of the shroud.

I have the RTI PPC in .22

Ask Rob.
Click to expand...

What does this hex screw do ? 

Don't want to mess with things that I don't know what they are for. That's one reason that's I'm HERE, asking you guys the questions. I like details, not just "do this" when you are messing with things that I don't know what they do.



NOTE - I also need to let it sit for about two weeks like the last sit, period to see it it leaks down like it did. I'll put another magazine thru it, refill it, and put it away, to see what happens.



Mike
Click to expand...

You can ask RTI and explain the issue, Mr. Rob, the owner is the one replying and he will guide you through the solution.


 
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Yes sir. Especially when I realized that I didn't need to go any further testing joints ! I was at my last "outer" possible leak point. Any further testing would have meant taking things apart ! Well, I guess I did have one more possible, semi-outer leak point, but it still would have meant taking the butt plate off, and checking the degas port.



Yes, it feels good !



Mike
 
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