N/A FX Impact M3 setup/Tuning advise please

[dye29]

hi all so I just got a fx impact m3 600mm .22 with slug liner . everything I try too shoot is all over when I tune with fx true ballistics chrono I find max speed for that reg then shave off 10-15fps with valve then use hammer wheel for best group , this always works with my m2 anyway .
so I shoot and get like 980 then 960 then 1000 unsure why really so im trying to go back to basics , what size hammer spring , valve spring needed please . im using 8.3gram weight and the stiff valve spring approx 42mm the hammer spring is stock . im now thinking could the reg be at fault ?

 

[MongooseV8]

I think you are adjusting the Hammer and Valve stop in opposite order most people do. I set my reg pressure, then find the fastest speeds with the hammer while leaving the valve stop full open. Then dial down the speed about 3% or so with the hammer adjustment, and finally dial in groups with small changes to the valve stop.

On my Impacts the hammer wheel was always at max, and I use the fine tune to make any hammer adjustments. To do this on an Impact you really need to have your hammer weight and spring matched with your reg setting. I have found that too much or too little hammer strike "range" will produce erratic fps ranges on all my FXs. This is why I have a pile of different sized weights and springs so I can have a nice balanced setup no matter what level of performance I need.

In your 22Cal you likely wont need any aftermarket parts to find a good balance. But FX has been known to install the wrong parts at the factory, or maybe you are pushing your rifle beyond what is possible out of the box. What ammo weights are you testing?

 

[Trucker3573]

In my opinion it is all about balancing the hammer strike, reg pressure, projectile weight and valve spring. Hammer strike has to be in harmony with all this to obtain consistency. When you start changing things it becomes even more complex. Something as simple as using the wrong weight hammer or spring can throw a wrench in. I learned this with my wildcat bt. It originally came as a .30 caliber. I changed to .25 and tried to tune for 33.95 pellets with the 30 cal hammer weight which is heavier. I couldn’t get a really good consistent tune in the speed range for pellets with that 30 hammer. I bought a 25 cal hammer weight which is only slightly lighter and it made it a new gun in .25. Tuned beautifully and easily to a bit over 900 fps with the heavies with that simple change. All about balancing everything.

 

[coastal drifter]

I also tune reg, hammer then valve for final tweaking. I have the same gun/barrel length/caliber (superior barrel). Shoot the 18gr pellets with reg set at 70bar 900fps and the 27gr H&N hp 970fps reg setting 135bar. All factory equipped.