FX Wildcat MK3 BT Random FPS Drop in Shot String (Update Post #16- 4/12/24)

[ocdairgunner]

UPDATE: 4/12/24 Post #16

Recently acquired a used Wildcat MK3 BT in .30 cal, 600mm barrel and a 580cc CF bottle.

I have been shooting it to get accustomed and after having shot about 200 + pellets (JSB 44.75 gr) I took to my chronograph to see how it is shooting.

With the power wheel set to 7, I noticed over a 36 shot string that it will shoot consistently but 3-4 shots will be 30-35 fps lower than the average. My rear manometer (WIKA) is set around 118-120 BAR and do not see it move around from shot to shot. Have not checked the front regulator pressure yet.

I have attached a few pictures of the area of the pellet probe and the reg gauges for reference

Another thing (see attached picture) is that every time I shoot, a puff of air comes out this hole in the barrel. Is this normal? Should there even be a hole there?

Thank you for the input.

See my string shot below and please advise what could be causing this issue.

Hole where a puff of air comes out after each shot

36 shot string:

885, 886, 888, 892, 894, 883, 891, 890, 890, 890, 890, 886, 888, 862, 864, 881, 896, 892, 894, 891, 891, 888, 894, 888, 891, 886, 879, 879, 863, 869, 891, 889, 896, 895, 895, 890

 

[Loff]

That hole, where that puff of air comes, is shroud vent hole. It is normal.

With what are You measuring speed, what chrono?

 

[Headshots]

Are you familiar with hammer spring adjustments ?. You could turn the PW setting down to 6 and see if your fps speeds up . If it does try 5 . You could be over the peak HS setting . If not, you can increase HS tension to find its peak fps . Then turn it down by 10% or so .

 

[Emu]

Manometer is not a regulator.

Manometer measures preassure. Front manometer (Huma) is measuring the pressure of your bottle. Rear manometer (Wika) measures the regulated pressure of the plenum.

 

[ocdairgunner]

That hole, where that puff of air comes, is shroud vent hole. It is normal.

With what are You measuring speed, what chrono?

Thanks good to know the hole is normal.

I am using Pro Chrono DLX. I measured this string this morning when it was cloudy outside. Did not use those shades that come with it

 

[ocdairgunner]

Are you familiar with hammer spring adjustments ?. You could turn the PW setting down to 6 and see if your fps speeds up . If it does try 5 . You could be over the peak HS setting . If not, you can increase HS tension to find its peak fps . Then turn it down by 10% or so .

I turned the HS counterclockwise and i was in the 915 fps range but turned it clockwise again because I believe pellets give best accuracy around 890ish range. I will have to do more tests by turning the wheel to 7 and turning the HS counterclockwise until I do not see the fps rise and then bring it back 10% fps wise like you suggested and see if my shot string stabalizes.

 

[ocdairgunner]

Manometer is not a regulator.

Manometer measures preassure. Front manometer (Huma) is measuring the pressure of your bottle. Rear manometer (Wika) measures the regulated pressure of the plenum.

Got it. Thanks

 

[Headshots]

I turned the HS counter clockwise and i was in the 915 fps range but turned it down because I believe pellets give best accuracy around 890ish range. I will have to do more tests by turning the wheel to 7 and turning the HS counterclockwise until I do not see the fps rise and then bring it back 10% fps wise like you suggested and see if my shot string stabalizes.

So to me that would indicate the 2nd reg pressure is to high for the pellet weight and speed your looking for . My Maverick doesn't respond well when it's out of tune . It's that balance between plenum pressure and valve stem pressure and hammer spring weight and spring tension. Also you could find its peak, if it's 915 or so your probably gtg. And i usually don't go 10 percent less it's more like 10-20 fps . Be careful not to adjust it so far it won't stay cocked with a mag of pellets in it . It's easy to double load . I find the point it won't stay cocked before hand so I would know how many turns I have . Have fun

I'm a rookie and there a ton of information on this site . Lots of. 30 cal shooters. And seasoned airgunsmiths .

 

[ocdairgunner]

So to me that would indicate the 2nd reg pressure is to high for the pellet weight and speed your looking for . My Maverick doesn't respond well when it's out of tune . It's that balance between plenum pressure and valve stem pressure and hammer spring weight and spring tension. Also you could find its peak, if it's 915 or so your probably gtg. And i usually don't go 10 percent less it's more like 10-20 fps . Be careful not to adjust it so far it won't stay cocked with a mag of pellets in it . It's easy to double load . I find the point it won't stay cocked before hand so I would know how many turns I have . Have fun

I'm a rookie and there a ton of information on this site . Lots of. 30 cal shooters. And seasoned airgunsmiths .

Thank you! I will have to play around with the second reg and lower it to 90 bar and first at 120-125 bar and see what kind of results I get

 

[Bigragu]

The two m4 grub screws that hold the cocking block to the rod that moves the pellet probe back to forward , are working themselves loose and before long, you’ll really suffer a permanent lose of velocity like by 100 fps. It’s best to replace the two screws to socket head screws instead of trying to tighten up the factory grub screws repeatedly, and rounding off the Allen socket, then you’re really screwed.
Or, if you’re feeling spendy, replace them with Torx head grub screws. On both my wildcats I replaced them with Torx socket heads cause I didn’t realize Torx grubs were available at the time, but you pay for their convenience.

On the four barrel lock set screws on my Crown MK2, those are switched out to Torx set screws. I would’ve used socket head Torx but the angle of the screws entry don’t allow for that

 

[ocdairgunner]

The two m4 grub screws that hold the cocking block to the rod that moves the pellet probe back to forward , are working themselves loose and before long, you’ll really suffer a permanent lose of velocity like by 100 fps. It’s best to replace the two screws to socket head screws instead of trying to tighten up the factory grub screws repeatedly, and rounding off the Allen socket, then you’re really screwed.
Or, if you’re feeling spendy, replace them with Torx head grub screws. On both my wildcats I replaced them with Torx socket heads cause I didn’t realize Torx grubs were available at the time, but you pay for their convenience.

On the four barrel lock set screws on my Crown MK2, those are switched out to Torx set screws. I would’ve used socket head Torx but the angle of the screws entry don’t allow for that

Bigragu, the m4 screws on the cocking block are nice and snug. However, I will go ahead and replace them with torx head screws. What size are they in length?

 

[Chukar60]

Bigragu, the m4 screws on the cocking block are nice and snug. However, I will go ahead and replace them with torx head screws. What size are they in length?

I just put blue Locktite on mine. That was two years ago and they have not budged.
If you go that’s route do the one at a time. Do not remove both grub screws at the same time. Voice of experience here.
Even if that is not your current problem, without some preventative measure it will be a problem.

 

[ocdairgunner]

So to me that would indicate the 2nd reg pressure is to high for the pellet weight and speed your looking for . My Maverick doesn't respond well when it's out of tune . It's that balance between plenum pressure and valve stem pressure and hammer spring weight and spring tension. Also you could find its peak, if it's 915 or so your probably gtg. And i usually don't go 10 percent less it's more like 10-20 fps . Be careful not to adjust it so far it won't stay cocked with a mag of pellets in it . It's easy to double load . I find the point it won't stay cocked before hand so I would know how many turns I have . Have fun

I'm a rookie and there a ton of information on this site . Lots of. 30 cal shooters. And seasoned airgunsmiths .

So I went ahead and reset everything because I wanted to get to a baseline.

Here is what I did so far:
1) Degassed the plenum and lowered the regulator pressure for both the front and rear to this: 95 bar rear reg and 125 bar front reg. I shot a 30 shot string with this new setting and average 830 fps using JSB 44.75 gr (power wheel at 7) with a spread of 25fps (better than before but I knew I could tighten this more). Step 2 below had not been performed yet.
2) I used this guide from Utah Airguns to correct my timing. I believe this was the main reason for getting rid of the erratic shots (see new shot string below).

3) I turned the HS all the way in, clockwise, so it bottomed out. Then I shot the string you see below.

- Turning the HS counterclockwise half a turn from bottom did not increase my velocity.​

- I am assuming to get more velocity, I would need to turn up the rear reg pressure???​

The two m4 grub screws that hold the cocking block to the rod that moves the pellet probe back to forward , are working themselves loose and before long, you’ll really suffer a permanent lose of velocity like by 100 fps. It’s best to replace the two screws to socket head screws instead of trying to tighten up the factory grub screws repeatedly, and rounding off the Allen socket, then you’re really screwed.
Or, if you’re feeling spendy, replace them with Torx head grub screws. On both my wildcats I replaced them with Torx socket heads cause I didn’t realize Torx grubs were available at the time, but you pay for their convenience.

On the four barrel lock set screws on my Crown MK2, those are switched out to Torx set screws. I would’ve used socket head Torx but the angle of the screws entry don’t allow for that

I just put blue Locktite on mine. That was two years ago and they have not budged.
If you go that’s route do the one at a time. Do not remove both grub screws at the same time. Voice of experience here.
Even if that is not your current problem, without some preventative measure it will be a problem.

@Bigragu @Chukar60 I took your advice and looked at the video I shared above from Utah Airguns to correct my timing. This helped me get rid of the erratic shots and really tightened my ES as you can see from the shot string below.


827, 832, 832, 830, 826, 829, 831, 829, 832, 829,832, 834, 834, 831, 835, 833, 832, 835, 835, 834, 830, 831, 831, 834, 831, 835, 833, 832, 835, 835, 834, 832

This is my first time ever tuning a PCP (Had a Daystate Air Ranger prior to this which was set-up fine the way it was so never tinkered). What would you all recommend at this point to fine tune the current tune? Raise rear reg pressure? By how much? What about the HS? It is currently fully turned in clockwise.
I want a good balance of power (want to get back to 890ish fps or 80 fpe) with 44.75 JSB but still retain a a decent shot count. Currently, it will do 5 mags (13 per mag) from 250bar to 130bar. Prior to the tune was getting similar shot count.

 

[Headshots]

So I went ahead and reset everything because I wanted to get to a baseline.

Here is what I did so far:
1) Degassed the plenum and lowered the regulator pressure for both the front and rear to this: 95 bar rear reg and 125 bar front reg. I shot a 30 shot string with this new setting and average 830 fps using JSB 44.75 gr (power wheel at 7) with a spread of 25fps (better than before but I knew I could tighten this more). Step 2 below had not been performed yet.
2) I used this guide from Utah Airguns to correct my timing. I believe this was the main reason for getting rid of the erratic shots (see new shot string below).

3) I turned the HS all the way in, clockwise, so it bottomed out. Then I shot the string you see below.

- Turning the HS counterclockwise half a turn from bottom did not increase my velocity.​

- I am assuming to get more velocity, I would need to turn up the rear reg pressure???​

@Bigragu @Chukar60 I took your advice and looked at the video I shared above from Utah Airguns to correct my timing. This helped me get rid of the erratic shots and really tightened my ES as you can see from the shot string below.


827, 832, 832, 830, 826, 829, 831, 829, 832, 829,832, 834, 834, 831, 835, 833, 832, 835, 835, 834, 830, 831, 831, 834, 831, 835, 833, 832, 835, 835, 834, 832

This is my first time ever tuning a PCP (Had a Daystate Air Ranger prior to this which was set-up fine the way it was so never tinkered). What would you all recommend at this point to fine tune the current tune? Raise rear reg pressure? By how much? What about the HS? It is currently fully turned in clockwise.
I want a good balance of power (want to get back to 890ish fps or 80 fpe) with 44.75 JSB but still retain a a decent shot count. Currently, it will do 5 mags (13 per mag) from 250bar to 130bar. Prior to the tune was getting similar shot count.

I would give the HS a few more turns ccw and see if it speeds up the fps . If not then ya you would need more pressure. I walk the pressure up slowly and keep the HS in balance. You need to know where the peak or knee is and you want to back off the HS adjustment 10-20 fps. It will quiet down and save you a bunch of air .

You should see the fps increases when your adjusting hs ccw. You do that until the fps slows down , that's the knee or peak. And it takes a few shots after adjusting it so the the changes settle in . Don't go cranking the adjusting screw cw on the regs when under pressure. You'll have problems.

Good luck .

 

[ocdairgunner]

I would give the HS a few more turns ccw and see if it speeds up the fps . If not then ya you would need more pressure. I walk the pressure up slowly and keep the HS in balance. You need to know where the peak or knee is and you want to back off the HS adjustment 10-20 fps. It will quiet down and save you a bunch of air .

You should see the fps increases when your adjusting hs ccw. You do that until the fps slows down , that's the knee or peak. And it takes a few shots after adjusting it so the the changes settle in . Don't go cranking the adjusting screw cw on the regs when under pressure. You'll have problems.

Good luck .

Thanks for the straightforward and easy to follow instructions. Will update once I have everything in balance and working in harmony

 

[ocdairgunner]

Update:

If any of you saw my other thread. I went through a mess to get the Wildcat working because the threads on the front bottle adapter and the bottle valve were cross threaded.

Anyway, I put a new bottle adapter (https://utahairguns.com/product/fx-dream-tac-dream-lite-bottle-adapter/) and a new M3 bottle valve from Talon Tunes and got my Wildcat up and running again.

Unfortunately I am still getting drops in FPS when shooting from 250 bar down to 120bar.

My front regulator is at 145 and rear at 120. I played around with the hammer spring settings. Before doing all this, I took out the hammer assembly cleaned it up, including the spring and hammer weight. Important thing I saw and noted were the two washers on the hammer: is that normal and from factory or something the previous owner added? It is a used gun.

Then I followed the video from Ernst Rowe and turned the HS CCW until I did not gain any FPS. At this current setting ( 120 bar rear reg and power wheel at 7) I got around 910-915 fps. Turning the HS CCW further started dropping FPS so I turned it CW until I was in the 880-885 fps range.

I am getting really good accuracy at this setting, however when I shoot with these parameters from 250bar to 120bar I would get really tight ES of 7-9 fps for 13-15 shots and then would get 3-5 shots that would drop fps to 855-860 and then creep back up to 880-885 and stay this way until my bottle pressure dropped down to the rear reg pressure of 120bar. I can feel and hear the gun not shooting strong when this drop happens. The chronograph confirms what I can hear and feel in the shot cycle.

Any idea what is causing this?

Thanks guys