FX Help with tuning Wildcat down

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bchannell

bchannell

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Nov 1, 2020
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Parkersburg, WV USA
I'm new to the WC, but not FX, as I have a Crown and Dream Tac, and have had Impacts etc. But, I have a question about the WC tune.

I want to tune it down to shoot 18gr pellets for a while, and am having trouble getting below 950 fps.
My current tune is
1st reg ~135 bar
2nd reg 80 bar
hammer 1 ( hammer screw is at 5.25mm and hammer weight is 11.4g)

Do I need to go to a lower hammer weight for pellets? My thinking was that 11.4g is the factory original hammer weight for 22 cal. So I'm not sure how to go a bit lower.
 
bchannell said:
I'm new to the WC, but not FX, as I have a Crown and Dream Tac, and have had Impacts etc. But, I have a question about the WC tune.

I want to tune it down to shoot 18gr pellets for a while, and am having trouble getting below 950 fps.
My current tune is
1st reg ~135 bar
2nd reg 80 bar
hammer 1 ( hammer screw is at 5.25mm and hammer weight is 11.4g)

Do I need to go to a lower hammer weight for pellets? My thinking was that 11.4g is the factory original hammer weight for 22 cal. So I'm not sure how to go a bit lower.
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Is the micro adjuster screw backed down? I was around 900 fps with a 700mm at 130 bar for the impact and my shooting partners 500mm mav was very similar (wc in a chassis).

You have me wondering if you've got a 12-14 hammer weight in there too. Luckily hammer changes are fantastically simple on that platform.
 
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Ok, I'm learning. I've tuned Impacts and not had any problems, but the ones I had were not Wildcats that's for sure. I've fiddled with everything on it and pellets in the fast twist barrel is a no go for consistency. Accuracy at 30m was one hole, but we all know further out it's not for sure. I tried both reg settings and everything was a 40,,50 even 100 fps spread, but I was changing hammer settings and not letting it settle in (I'm not sure why that matters but I've found it does). After a few sessions and walking away to clear my head, I decided to try some Zan slugs.
25.5gr Zans, 1st reg 155 bar, 2nd reg 120bar, hammer on 7, hammer screw is 4.1mm out, and 915 fps avg with around 3 fps spread. Holy cow! what a turnaround!!!!!

I'm guessing this liner just don't like pellets.
 
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Scotty1 said:
If you raise your reg pressure, without adding more hammer energy, your fps will of course drop. Maybe try 100 bar… it’s free to try it.
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This is my suggestion too. When I was shooting 18 jsb it was 12g hammer, 130 bar. I paid 50 bucks for a tune from UA because I believed all the fear hype about tuning. It's super easy cause and effect.
 
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As for springs there are only 2 FX uses, a 52mm and a 56mm spring. There are aftermarket springs available at different rates. I agree with the others above you can slow things way down with the hammer pre-load screw.

As for the liner, I would be surprised if you have an FX STX standard liner that doesnt like to shoot pellets. While it has happened, its rare to get one that wont do well with the usual pellet sellection.
 
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I'm still tuning and thinking things thru. Thanks for the help.
I'll try lower pressures again.
I read a piece that suggested that large plenum don't play well with lighter power tunes as the plenum doesn't dump enough air per shot to refill properly on each shot. Makes sense.

Also same post suggested to shoot pellets, it is possible to reverse the plenum tube on bottle guns (which mine is) and position the reg closer to the block lowering the plenum size. Also makes sense but I'm doubting you need to do all that just to shoot pellets.
 
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The plenum will fill a little slower between shots if you have the final reg set low like you do, but it shouldnt prevent you from getting good accuracy. There are a lot of Wildcat and Maverick owners with 22Cal setups that get fantastic accuracy at normal pellet speeds. Are you trying to shoot low power or just get good groups with pellets and your rifle wont go slow enough?
 
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I would leave the reg alone and get your hammer strike under control. You are still hitting too hard. A few turns is not going to be enough, keep going til you start to see speeds drop and you get your tuning control back. If you get to the point where the screw is all the way in, and you still dont have control over your hammer strike at a low reg setting you can then consider going to a lighter hammer weight.

ETA: I thought you were on power wheel 1, but your last post says 7. What happens when you set it to like 4? Still high fps with erratic ES? That is a sign your hammer strike is way too hard. It might be a better idea to start from the hammer pre-load screw all the way in and work your way out until you lose tune control.
 
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Screw the IHS in all the way and if that is not enough raise your 2nd reg until the plenum pressure starts shutting the valve faster. If you want 880 fps or so, raise the 2nd reg until your velocities drop to about 820-830 fps. Then you can start backing the IHS out until you get to the 880’s. You now are close to your desired velocity and have some tune room on the IHS. The other benefit is you will be getting a nice short pulse of air. Whenever I see velocity deviations like you have it is almost always a case of too much hammer strike.
 
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Chukar60 said:
Screw the IHS in all the way and if that is not enough raise your 2nd reg until the plenum pressure starts shutting the valve faster. If you want 880 fps or so, raise the 2nd reg until your velocities drop to about 820-830 fps. Then you can start backing the IHS out until you get to the 880’s. You now are close to your desired velocity and have some tune room on the IHS. The other benefit is you will be getting a nice short pulse of air. Whenever I see velocity deviations like you have it is almost always a case of too much hammer strike.
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Great advice. Start super low with hammer and see where you are at. I suspect if the hammer is still too much all the way down for 90 bar the weight in there is too heavy or the spring too stiff. I had a Mav compact in .25 and could run 90 bar reg no problem without over powering it.

Did you buy the gun new ??

Edit…just noticed you said the weight was 11.4. You should have no problem running that low of a reg. However that doesn’t mean the gun wont over power 18 gr pellets. What length barrel ??

Someone mentioned running a high reg with lighter hammer strike. I have never found that combo to produce consistent performance. Best performance is a harmonic balance between the two. Running a high reg pressure to just open the valve a small amount is not a harmonic balance in my opinion. Maybe just me. I don’t like running more reg than necessary to do what I need. Mine is 30 cal 600mm and only need 115 bar to produce a very consistent 80-81 ft/lbs.
 
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Ok, here's what I found out.
18.1gr pellets are a no go at any reasonable fps. You need to really go high, like over 1000 fps to get any kind of consistency and then you're wasting air tremendously and consistency is only so-so.

JSB MRD's are the pellet that gets in the sweet spot of this rifle. Anything less than the mid to high 800's is pretty decent, but up the fps to 900-905 and you're golden.
The tune:
1st reg, ? I opened it a quarter turn as I was raising the 2nd reg while tuning
2nd reg 110
Hammer 3 turns out (3.62mm out) wheel set on 7
905 avg, 7.7 es and accuracy looks very good indeed.

The Wildcat is definitely a hot shooting rifle. The hotter it goes, the better it likes it.

Has anyone tried turning the air tube between the block and barrel around and shortening the plenum?
 
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