Tuning BRK Ghost .22 HP not producing power any suggestions?

[robertwalsh1981]

I have been tinkering with my Ghost, swapped springs out for the White spring and then Blue spring, and testing different reg pressures and now it is only able to achieve ~620 FPS with the following configuration.

BRK Ghost .22 HP
23" barrel
Red Hammer Spring
Tank ~190 BAR
Reg ~165 BAR
PW Max
JSB Exact RS Diablo 13.43 gr.
FPS = 622 (highest)

When it first arrived it was cranking the JSB Hades 15.89 gr pellets at close to 1030 FPS with the following configuration:

BRK Ghost .22 HP
23" barrel
Red Hammer Spring
Tank ~190 BAR
Reg ~150 BAR
PW Min
JSB Exact RS Diablo 15.89 gr.
FPS = 1030

I am charging it from a Yong Heng compressor with this secondary water/oil separator in line between the compressor and the gun.


I should also mention that when degassing the gun it is taking 15+ shots with the PW on MAX setting before the reg pressure drops below 50 BAR, not sure if this is relevant, but from my limited experience/knowledge it seems to indicate that perhaps the valve is not opening fully?

Any thoughts or suggestions on what might cause this behavior?

 

[robertwalsh1981]

Yeah you would expect fps to flatline (almost) at some point at that pressure. But there isn’t too much of a difference between blue/red/yellow so the relation of speeds make sense to me.

That said, there seems to be something stopping your valve from fully opening and the stronger the spring the more it is opening. Did you check the hammer for “lost” pieces? I think to remember that someone had a damaged hammer (which would give you a lighter hammer - too light). If that isn’t it either you’ll have to pull the valve I guess. Ah and maybe check that the power wheel is properly aligned and not loose (there is a set screw in there, if it’s loose you may basically be shooting on min all the time).

Yeah, pulled the hammer and it looks to be intact with no obvious damage, also while testing I ran through the PW settings from Min to Max and saw changes in FPS from the bottom to the top with the White spring. I didn't repeat those steps with the other springs as the PW appeared to be working as expected. Sounds like I get to do a deep dive into the valve sooner than I was expecting, oh well, it should be educational!

 

[greenbeans]

That’s really really weird… in particular if you only changed springs back and forth but nothing else’s touched… Anyway, if hammer good, spring good, PW good, barrel o rings and TP/probe alignment good all that remains is valve and reg, so you’ll get there eventually will be interesting to know once it is sorted out.

 

[robertwalsh1981]

Or the regulator gauge?

Is this a relatively new Ghost? Or did you pick it up used?
Where I'm going with that question is that early ones had a threaded extension in the nose of the hammer....if that's the case, and it worked its way loose, that would make it very hard to increase the fps, as your hammer "throw" would be minimized by the effectively longer hammer, and reducing the hammer strike on the valve.

Just saw this one, it is a new Ghost the hammer is a single piece of metal without an adjustment screw on the nose.

 

[robertwalsh1981]

That’s really really weird… in particular if you only changed springs back and forth but nothing else’s touched… Anyway, if hammer good, spring good, PW good, barrel o rings and TP/probe alignment good all that remains is valve and reg, so you’ll get there eventually will be interesting to know once it is sorted out.

Before the issue began I had changed springs and played with the regulator increasing/decreasing reg pressures to see how various pellets were shooting. Once the issue began I pulled the rear of the Ghost and checked the hammer etc. but did not find anything. I have not touched the valve, and all that I have done with the regulator is adjusting it up or down (degassing the gun for down). This has me scratching my head as I cannot recall any action on my part that would account for the behavior, but then again once it gets sorted it will probably be one of those "OH YEAH, that happened" things that eludes memory for the moment.

 

[greenbeans]

Before the issue began I had changed springs and played with the regulator increasing/decreasing reg pressures to see how various pellets were shooting. Once the issue began I pulled the rear of the Ghost and checked the hammer etc. but did not find anything. I have not touched the valve, and all that I have done with the regulator is adjusting it up or down (degassing the gun for down). This has me scratching my head as I cannot recall any action on my part that would account for the behavior, but then again once it gets sorted it will probably be one of those "OH YEAH, that happened" things that eludes memory for the moment.

Hmmm if you played with the reg pressure a lot, how did you degas? Dry fire? A lot? Not sure about the Ghost valve but generally excessive dry fire isn’t a good idea with Airguns since there is no back pressure without a pellet/slug or the hammer hit the valve very hard at low pressure… generally better to degas by way of loosening the reg gauge a bit until it starts hissing

 

[robertwalsh1981]

Hmmm if you played with the reg pressure a lot, how did you degas? Dry fire? A lot? Not sure about the Ghost valve but generally excessive dry fire isn’t a good idea with Airguns since there is no back pressure without a pellet/slug or the hammer hit the valve very hard at low pressure… generally better to degas by way of loosening the reg gauge a bit until it starts hissing

I was dry firing as that was how it was shown in the BRK tutorial videos, I have been degassing via loosening the reg gauge since the issue as dry firing would take a crazy number of shots (probably more than 20)

 

[greenbeans]

I was dry firing as that was how it was shown in the BRK tutorial videos, I have been degassing via loosening the reg gauge since the issue as dry firing would take a crazy number of shots (probably more than 20)

Yeah their video is dry fire, same for other makers’ tutorials… it’s probably fine anyway, I just avoid dry fire in general…

 

[Franklink]

Just saw this one, it is a new Ghost the hammer is a single piece of metal without an adjustment screw on the nose.

Then that rules out the adjustable hammer as a source.

Again, head scratcher.

I'll keep thinking on it and will let you know if I come up with any ideas.

 

[Franklink]

I just remembered that I've read of a handful of instances where the hammer got bound up....


If you put in one of the lighter springs and back the power wheel down to "min" you should be able to hear the hammer clunck back and forth if you tip the front of the gun up and down. The Ghost has a free float hammer with minimal hammer tension. You might be able to use that to determine if your bound up somehow.

Also, there's an L bracket (cocking bracket) that fits into the dovetail in the top of the hammer. Held in place by two grub screws. Is that L shaped cocking bracket seated all the way to the rear of the dovetail in the hammer?

 

[robertwalsh1981]

I just remembered that I've read of a handful of instances where the hammer got bound up....


If you put in one of the lighter springs and back the power wheel down to "min" you should be able to hear the hammer clunck back and forth if you tip the front of the gun up and down. The Ghost has a free float hammer with minimal hammer tension. You might be able to use that to determine if your bound up somehow.

Also, there's an L bracket (cocking bracket) that fits into the dovetail in the top of the hammer. Held in place by two grub screws. Is that L shaped cocking bracket seated all the way to the rear of the dovetail in the hammer?

Ironically I just finished reading one of the threads that discussed the hammer getting bound up. After reading your comment above I went and verified that with the Blue spring and the PW set MIN I can hear the hammer sliding freely when I tip the gun forward/backward. I did verify that the cocking bracket was fully seated in the dovetail on the hammer when I had it apart earlier today.

After reading that article I was worrying about perhaps having damaged the hammer due to dry firing it to/below 50 BAR when adjusting the reg down, but the hammer did not appear to be damaged and I did not see any of the "bulging" that was mentioned in that thread.

A little bit ago, I degassed the gun to zero, pulled the rear off and then tried pushing on the valve (where the hammer strikes it) by hand and it did not move, I then tapped (and I mean tapped, I did not whack it) it with a small hammer using an acrylic handle off of an interchangeable screw driver as a "punch" (between the valve and hammer), which also did not appear to move the valve at all.

I think my next step would be to pull the valve out and see if there is any indication of damage or binding internally, though I am not sure how there would be.

 

[Solo1]

After all that i’d have to say check the reg and see if everything looks good.

 

[Franklink]

With no air in the gun, the valve stem should be pretty easy to depress. Here's a short little clip of what that looks like with a valve out of the gun...

Easily depressed with thumb alone. If it's taking more than that, you got a problem....and that problem could be that the gun actually still has air in it (gauge isn't reading correctly) or that your valve stem is in a bind somehow (bent?).

I've personally avoided the degas by firing method for awhile now....every leaky valve I've had happened shortly after a tuning session where I needed to drop the reg and emptied the gun of air by firing a bunch of times. Coincidence? Possibly. But because of that I've been degassing by cracking the manometer slightly. And trying not to need to degas very often.

As for removal of the valve....here's my homemade little tool. It works fine. I've been told that it's possible with just the drill bits (or ideally correct diameter pins) and the crescent wrench. But I prefer using my little scrap of flat metal with holes to kinda secure the pins. The first time you loosen that valve retaining disc will be the hardest. Dunno why but it's over tightened from the factory.

Finally, the leaky valves I've had didn't have any visible defects on the valve stem. One of them I was able to spin the valve stem with a hand drill against the face of the valve where it seats and then got it holding air again. The other required a new valve. Each time I tried to just get a valve stem replacement but AOA replaced the entire valve assembly. And it being like a faucet/shower cartridge, it's just a pull the old one out and pop the new one in situation.

It's interesting that yourz isn't leaking, but seems to maybe have the valve stem (partially?) bound up. I'm not sure the valve is the problem, but we seem to have ruled out the other most obvious culprits.

 

[robertwalsh1981]

With no air in the gun, the valve stem should be pretty easy to depress. Here's a short little clip of what that looks like with a valve out of the gun...

Easily depressed with thumb alone. If it's taking more than that, you got a problem....and that problem could be that the gun actually still has air in it (gauge isn't reading correctly) or that your valve stem is in a bind somehow (bent?).

I've personally avoided the degas by firing method for awhile now....every leaky valve I've had happened shortly after a tuning session where I needed to drop the reg and emptied the gun of air by firing a bunch of times. Coincidence? Possibly. But because of that I've been degassing by cracking the manometer slightly. And trying not to need to degas very often.

As for removal of the valve....here's my homemade little tool. It works fine. I've been told that it's possible with just the drill bits (or ideally correct diameter pins) and the crescent wrench. But I prefer using my little scrap of flat metal with holes to kinda secure the pins. The first time you loosen that valve retaining disc will be the hardest. Dunno why but it's over tightened from the factory.
View attachment 531040


Finally, the leaky valves I've had didn't have any visible defects on the valve stem. One of them I was able to spin the valve stem with a hand drill against the face of the valve where it seats and then got it holding air again. The other required a new valve. Each time I tried to just get a valve stem replacement but AOA replaced the entire valve assembly. And it being like a faucet/shower cartridge, it's just a pull the old one out and pop the new one in situation.

It's interesting that yourz isn't leaking, but seems to maybe have the valve stem (partially?) bound up. I'm not sure the valve is the problem, but we seem to have ruled out the other most obvious culprits.

Yeah, my valve is not moving at all via hand pressure and if it moved when I was tapping it with the hammer I couldn't see it. That along with the fact that I am seeing increases in FPS when installing stronger springs would seem to indicate the issue may be in the valve. I appreciate the info and pic of your tool for valve removal, just to verify, if I have cracked the monometer and let the air bleed down until both gauges read zero then there should not be a way for there to be high pressure air still in the valve system right?

Additionally, I remembered that the first time I lowered the reg pressure I removed the bottle but forgot to degas the regulator and I adjusted it downward. That was a couple of weeks ago and it had been shooting perfectly with reg adjustments seeming to work since then so I am not sure if it would be related, but I figured it was worth mentioning.

 

[Franklink]

Yeah, my valve is not moving at all via hand pressure and if it moved when I was tapping it with the hammer I couldn't see it. That along with the fact that I am seeing increases in FPS when installing stronger springs would seem to indicate the issue may be in the valve. I appreciate the info and pic of your tool for valve removal, just to verify, if I have cracked the monometer and let the air bleed down until both gauges read zero then there should not be a way for there to be high pressure air still in the valve system right?

Additionally, I remembered that the first time I lowered the reg pressure I removed the bottle but forgot to degas the regulator and I adjusted it downward. That was a couple of weeks ago and it had been shooting perfectly with reg adjustments seeming to work since then so I am not sure if it would be related, but I figured it was worth mentioning.

In theory, if you cracked the gauges open and heard the air escaping then the chassis should be empty of air. Unthread the regulator gauge a bit more just to verify that you're on E.

I'm not sure if the regulator can survive trying to adjust down when under pressure the one time you're describing. I know it's highly advised against. BUT, if you were having appropriate/expected fps after that, I'm not sure that's the smoking gun in this problem you're trying to diagnose.

 

[robertwalsh1981]

In theory, if you cracked the gauges open and heard the air escaping then the chassis should be empty of air. Unthread the regulator gauge a bit more just to verify that you're on E.

I'm not sure if the regulator can survive trying to adjust down when under pressure the one time you're describing. I know it's highly advised against. BUT, if you were having appropriate/expected fps after that, I'm not sure that's the smoking gun in this problem you're trying to diagnose.

Forking this slightly, if the reg was damaged when I adjusted it down while under pressure, would it require replacement or just rebuilding the o-rings?

 

[greenbeans]

You can check whether your reg is the culprit by way of filling your bottle to say 19-20b more than your current reg setting. If you get good speeds at that bottle pressure then your reg isn’t actually regging and you have your hammer fight bottle pressure. Seems very unlikely though since this would require the reg gauge to be off as well plus still air in the rifle after degassing if the valve doesn’t move with finger pressure.

I’m starting to suspect valve bent or smashed in a bind while dry firing, which is obviously not your fault since that’s the way they tell you to degas. If it’s new it might be a good point in time to call the dealer and ask for a new valve.

 

[greenbeans]

Forking this slightly, if the reg was damaged when I adjusted it down while under pressure, would it require replacement or just rebuilding the o-rings?

Depends on damage but more likely replacement since adjusting under pressure deforms/scratches piston, adjustment screw and/or housing.

 

[robertwalsh1981]

You can check whether your reg is the culprit by way of filling your bottle to say 19-20b more than your current reg setting. If you get good speeds at that bottle pressure then your reg isn’t actually regging and you have your hammer fight bottle pressure. Seems very unlikely though since this would require the reg gauge to be off as well plus still air in the rifle after degassing if the valve doesn’t move with finger pressure.

I’m starting to suspect valve bent or smashed in a bind while dry firing, which is obviously not your fault since that’s the way they tell you to degas. If it’s new it might be a good point in time to call the dealer and ask for a new valve.

I was able to get the valve out and it definitely looks different than what is in the BRK strip down video. (I know there have been some changes)
From the video:

Pulled from my gun:

The internal end of the Valve Pin appears to have backed out with only a few threads holding it. Also by hand, I cannot get it to tighten down any further than where it is in the picture.

I put the valve back together and it will now depress slightly, but it does not appear to move to the extent that is shown in the video that was linked above.

Any thoughts?

 

[Arzrover]

Forking this slightly, if the reg was damaged when I adjusted it down while under pressure, would it require replacement or just rebuilding the o-rings?

Huma regs should not be damaged unless you really do something excessive...
Turning it down while under pressure usually makes a pock mark in the reg main seal disc and all that's required for the first instance is to flip it over. I think we can get new discs from Huma and maybe dealers or they can be made from a sheet of delrin or a rod if you have a lathe. Orings should not be affected nor any of the threads or other parts unless you go to extremes adjusting...
Bob

 

[Arzrover]

Your "valve pin" (valve stem) will need to be tightened so that the head is supported by the flared piece with the white oring. If it won't screw together, take it apart and clean it well and make sure none of the threads are damaged or cross threaded. You'll need to to Loktite it on final assembly. I don't think Red Loktite would hurt... you'll not want it to come apart, maybe ever...
Bob