Tuning FX Impact M3 tuning

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TMSFan

TMSFan

Member
Mar 29, 2018
37
8
Texas, United States
Good morning all. I am new to the M3 platform. I want to understand the gun prior to attempting to tune it. 
What exactly does the macro wheel, micro wheel and the valve adjuster do to the gun to affect the fps and how do they work together in the gun to shoot efficiently?

I’m going to be shooting FX pellets and FX Hybrid slugs. Does anyone have a starting tune?

I have a .25 cal, smooth twist with a 700 mm barrel. Thank you for all your help!!


 
Screwing the valve adjuster in will cause the valve to close quicker and hence reduce power. On the M3 with a 4-line valve adjuster, full open is 1.5 turns out from the 4th line. I'd leave it there to start with. Some people have used small changes in the valve adjuster to tune in slugs (normal slugs, not the FX Hybrids that I've heard of, but it may be possible). From my testing pellets work same or better with valve adjuster fully out and it is easier not having to mess with the valve adjuster.

Macro and Micro wheel both adjust the hammer spring tension. One click on the Macro wheel is about 10 clicks on the micro adjuster. The real indicator of where you are at is the marks on the micro adjuster. You could achieve same hammer tension different ways - less macro/more micro, and the reverse, as long as the micro adjuster indicator ends up at the same point. Recommend putting the macro wheel at 16 and do your adjustments on the micro to start.

I've found best accuracy in the 95-97% range for a given reg pressure. See here for explanation: https://hardairmagazine.com/ham-columns/tuning-regulated-pcp-airguns/

Here's a fast strategy to get a pellet tune. JSB pellets are known to fly well in the 850-900fps range, so pick a target velocity. In this case, lets pick 880fps.

  1. Max out your Macro and Micro hammer adjusters. Set them to 16 and 5. This is a quick way to see the max fps for a given reg pressure
  2. Shoot some shots across chrony and see what the max speed is for the current reg pressure. In this example target 97% velocity of 880 means we want ~907fps max. These shots will be LOUD since you are at overkill power and the valve may still be open when the pellet leaves the barrel.
  3. Leave hammer spring alone and adjust reg pressure as needed to achieve target max fps
  4. Once you get the reg pressure dialed in to achieve target max fps, dial back hammer spring via micro aduster until you hit the target final fps (880 in this case). Shots will get quieter since you are no longer wasting air.
  5. That should be pretty accurate, but if you want to tweak a little more accuracy, make small adjustments to the micro adjuster and shoot groups at different speeds within the 95-97% speed range.
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    I don't have experience with the FX hybrids, so can't help you there.

 
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