Tuning Fx Maverick hammer weight

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A_Emiliano8

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Apr 22, 2023
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Rochester, New York, United States
I recently purchased a Maverick vp .25 cal and was having difficulty tuning for 34gr JSB.

I was able to get and awesome JSB 25gr tune: 120/92 PW 7 IHS 7.5 turns clockwise (tightened) in from max giving an average 887fps ES of 4.1 and SD of 2.17.

The problem is that I could not, for the life of me, get the gun to shoot JSB 34gr. Tried a tone of veriatiobs. The one that would give me 880-890 was 160/130 PW 7 IHS at max. This was when I realized something was wrong. Called FX-USA and was told a few things:

The tech said you can identify which caliber hammer weight was in your gun by the length of the head/shoulder. .22 cal is 4mm, .25 cal is 6mm, and .30 cal is 8mm. He recommended measuring what was in my gun and order the others and just try them. Even though I have a .25 cal they put a .22 (4mm) hammer weight in my gun which is why I can’t hit the value hard enough to open for long enough to get the velocity I was looking for. FX-USA is sending me both the 6mm and 8mm for free under warranty. I will keep this thread updated with the results… hopefully I can correct the issue and get an awesome JSB 34gr tune to post here!
 
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Glad they got you sorted for free, still pretty lame you had to deal with it

itaylor00769 said:
Try turning your barrel over to dual ports set the 1st reg on 160 and the 2nd reg on 125 I have aVP Maverick shooting 34gr JSB 910 with the stock hammer weight
Click to expand...
his gun was delivered with less than stock hammer weight (22 cal weight in 25 cal config)
 
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itaylor00769 said:
Try turning your barrel over to dual ports set the 1st reg on 160 and the 2nd reg on 125 I have aVP Maverick shooting 34gr JSB 910 with the stock hammer weight
Click to expand...
As said above I was at 160/130 and hammer max getting 880-890. Essentially same tune. That is not right and you may want to pull your hammer weight, check shoulder length and get the right hammer.

I’m assuming with the correct hammer weight I can achieve 880-910 at 140/110. Should not need to work valves/ gun that hard for a pellet.

Could 100% tell my gun was not happy at 160/130 and neither was I, which was why I called and got sorted

Straight from FX- “regardless of barrel length should not have to go that high on regs and IHS to shoot 34gr if proper config.”

Cheers!
 
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From top to bottom in the pic below:
30cal
25cal
177/22cal
I bought a Maverick compact 22cal when they first came out. It maxed out at about 42-45 foot pounds with the stock hammer weight. I had FX send me the 25cal version and it maxed out at 850fps with a JSB 34 grain pellet or 55 foot pounds. The 25cal, which I have also should max out at 65 foot pounds with the King Heavies.
IMG_1533.jpeg
 
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I delt with this too, .25cal Maverick. Stock weight was 11g. I ordered the HumaAir power kit [hammers and pin probe] and their spring; tried all manner of combos and ended up with the 14gram hammer without the little spring washer and the Huma spring. 175bar with final reg at 145-ish bar. Port is set to dual side and the pin probe. 1017fps 30.86gr H&Npellets power wheel 7. 33.5gr NSA slugs are 983fps on these settings. 71 ft•lbs

Screenshot_20230419_203720_Chrome.jpg


20230419_200859.jpg

Obviously would back off the regs a little but that's the speed it gets.
 
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weevil said:
There’s also tungsten hammer if you’re looking to destroy your eardrum.
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Hahaha idk if I’m ready for that just yet. I heard the tungsten hammer is like 2x the weight. Just want to be able to shoot the 33.4gr JSB consistently with a reasonable reg pressure/tune. Once I’m good to go with Pellets then I’m going to move to slugs. I bought the FX hybrids, ZAN 34gr (I think) and javelin 36gr gen 2.
 
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The monster hammer I have [and havent tried] is 24grams. Noooooo thank you, lol. Utah Airguns in their regulator tuning video say 180 on first reg works dandy for them and 2nd reg at like 140bar maybe 150 I cant recall exactly.

I'll just take mine down a touch so I get 65ft•lbs with slugs and dial it down on the wheel to get pellets in the 905 range. It is loud in the ear as Maverick is alot less forward design than the M3. But quiet with a Donny. 175/145 isnt tearing anything up, except shot count.
 
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That’s the one thing I don’t like about my wildcat BT - the ting right next to the ear. I am tuned to use the stock 30 cal hammer (largest of the silver hammers in that photo above). I bought the Huma brass hammers and drilled out the largest one and installed a piece of PEEK rod. The modified hammer is the same weight as the FX 30 cal hammer but much quieter and lower in pitch. Tighter ES too!

FWIW, I found the FX 30 cal hammer was good thru 150bar, the heavy Huma 160bar. The Tungsten was just too unbearable to test. Huma also sells a power spring that’s a little longer and works well with their shorter brass hammer and provides a wider range of HST adjustment across power wheel settings. Useful if you want a tune that runs the gamut from a light pellet to a heavy slug from power 1 thru 7.
 
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One thing that now concerning me is a I didn’t have FX-USA send me a 52mm spring. So if I try the 13 gram .30 cal hammer weight I’m going to have to use my stock 56mm spring. 910 on YouTube says it may be a bit much/lose tunability. I may call them back tomorrow and have them send that as well so I have everything to try/find what works best. @DuncanHynes did you use the original 56mm spring that came with the gun?
 
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A_Emiliano8 said:
One thing that now concerning me is a I didn’t have FX-USA send me a 52mm spring. So if I try the 13 gram .30 cal hammer weight I’m going to have to use my stock 56mm spring. 910 on YouTube says it may be a bit much/lose tunability. I may call them back tomorrow and have them send that as well so I have everything to try/find what works best. @DuncanHynes did you use the original 56mm spring that came with the gun?
Click to expand...
My Wildcat was erratic with the factory 13gram hammer weight and 56mm spring. I couldnt find a happy tune regardless of reg pressure or hammer preload. Swapped in a 52mm spring after watching the 910 video and now have low single digit extreme spreads.
 
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