FX Tuning Fx Impact .30

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hgatesm

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Oct 1, 2022
25
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Carthage,bTexas, USA
Hello,

I have recently acquired an FX Impact M4 in .30 cal. 700mm barrel, tungsten hammer, slug probe.

I truthfully am very lost in trying to get this thing tuned, I thought I had it close a couple of times but then get to the range and end up running out of air before I can get to anything conclusive. I am having a hard time figuring out what setting to have the valve/regulator/wheels (macro/micro) at, I have watched several of the youtube videos out there and some information seems to be contradicting. I just want this gun to shoot accurately so any help would be greatly appreciated! Thanks in advance!
 
I have a 0.30 caliber, 700 mm barrel M3 tuned to shoot 44.8 grain domed FX diabolo pellets out to 60 yards.

At 60 yards outdoors I can put 20 consecutive shots inside a 2" tip to tip diamond target under normal wind conditions.

Indoors at 20 yards my 5 round group sizes are consistently between 0.036" and 0.40" edge to edge.

I tuned the rifle to "group size" Indoors at 20 yards.

Because I was testing 6 different brands/weights of pellets I set my plenum pressure to 120 bar for my heaviest pellet.

I began testing with the following settings: Air valve at 4, Macro at 8, Micro at 3.

I shot two 5 round groups for each pellet then increased the Macro 1 click and repeated.

I continued this process until the Macro was at 16.

I was fortunate that just 1 brand and weight of pellet outperformed the others. I then returned the Macro to the setting that produced the smallest group for that pellet.

I then advanced the Micro 1 click and shot two 5 round groups and continued this process until the Micro was maxed out. I then set the Micro to the setting that produced the best groups.

With the Macro and Micro set, I used a chrono to set the Air Valve. I turned the valve clockwise 1/4 turn, shot a 5 round group and continued this process until velocity just dropped. The rifle will also quiet down a fare amount.

Then I indexed the liner 1/8 turn clockwise, shot a 5 round group and repeated this process until the liner had been rotated 180 degrees. The POI shifts were ridiculous and the group size did NOT change and I was using a Targetshooting.com one piece rest and maintaining the same POA.

Once sighted back in at 20 yards, I took the rifle outdoors and shot groups at 20, 30, 40, 50, 60, and 70 yards. Past 60 yards the diabolos would spiral and the groups would open up a fare amount.

This is not the quickest way to tune an Impact but I enjoyed the process very much and learned a lot about my Impact and diabolo pellets.

Hope this helps.

Troy
 
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hgatesm said:
Hello,

I have recently acquired an FX Impact M4 in .30 cal. 700mm barrel, tungsten hammer, slug probe.

I truthfully am very lost in trying to get this thing tuned, I thought I had it close a couple of times but then get to the range and end up running out of air before I can get to anything conclusive. I am having a hard time figuring out what setting to have the valve/regulator/wheels (macro/micro) at, I have watched several of the youtube videos out there and some information seems to be contradicting. I just want this gun to shoot accurately so any help would be greatly appreciated! Thanks in advance!
Click to expand...
in My opinion there are 2 good ways to tune I’m aware of :
- first one is to max out your hammer spring and open valve adjuster. Then increase your reg until you get a speed about 3-5% above your desired speed. Then decrease your hammer spring again down until you reach your desired speed. And then close your valve adjuster until you see a slight drop in speed.
- second way is in below video :

have fun tuning!
 
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Why are you using a tungsten hammer? Not saying it is a wrong move but unless you need the extra force to launch heavy for caliber slugs at high speeds it will cause you more problems than it will solve. It will all but eliminate your hammer spring adjustability. It is another YouTube wonder of FX’s whose narrow application was never fully explained. Kind of like the 800mm barrel that got tons of press and then faded into oblivion for good reason. Both create more problems than they ever solved.
You can search threads here and see that lots of posts concerning the tungsten hammer are related to tuning problems and not as a solution to much of anything.
 
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Thank you ALL for the information! I went out to the range today and shot all of the air I had with me. Needless to say, it was a disaster.

I have seen better shot patterns out of birdshot at 50 yards. With some of the advice that yall have given me especially with the tungsten hammer. I put all of the original parts back in the gun. I was able to get some shots over my garage chorno setup and got it shooting at approximately 900fps with 44g diablo pellets.

I hope that tomorrow morning I will be able to get out to the range and test for any kind of accuracy. If I cant get any better results than I did today I really won't know what else to do.

Fingers crossed and hopefully I will have more feedback tomorrow!
 
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Trucker3573 said:
You left out a bunch of vital info but I will ask one question that may shed some light on the issue. I’m just speculating but I’m just throwing out there I bet it’s the tungsten hammer that is causing issues as I see this so much. What reg pressure are you trying to tune to ??
Click to expand...
I was advised by a shop to use the tungsten hammer because I was hoping to shoot slugs. I have taken that out for now and put back the original hammer, will try for accuracy again in the morning with pellets.
 
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Troy Bakel said:
I have a 0.30 caliber, 700 mm barrel M3 tuned to shoot 44.8 grain domed FX diabolo pellets out to 60 yards.

At 60 yards outdoors I can put 20 consecutive shots inside a 2" tip to tip diamond target under normal wind conditions.

Indoors at 20 yards my 5 round group sizes are consistently between 0.036" and 0.40" edge to edge.

I tuned the rifle to "group size" Indoors at 20 yards.

Because I was testing 6 different brands/weights of pellets I set my plenum pressure to 120 bar for my heaviest pellet.

I began testing with the following settings: Air valve at 4, Macro at 8, Micro at 3.

I shot two 5 round groups for each pellet then increased the Macro 1 click and repeated.

I continued this process until the Macro was at 16.

I was fortunate that just 1 brand and weight of pellet outperformed the others. I then returned the Macro to the setting that produced the smallest group for that pellet.

I then advanced the Micro 1 click and shot two 5 round groups and continued this process until the Micro was maxed out. I then set the Micro to the setting that produced the best groups.

With the Macro and Micro set, I used a chrono to set the Air Valve. I turned the valve clockwise 1/4 turn, shot a 5 round group and continued this process until velocity just dropped. The rifle will also quiet down a fare amount.

Then I indexed the liner 1/8 turn clockwise, shot a 5 round group and repeated this process until the liner had been rotated 180 degrees. The POI shifts were ridiculous and the group size did NOT change and I was using a Targetshooting.com one piece rest and maintaining the same POA.

Once sighted back in at 20 yards, I took the rifle outdoors and shot groups at 20, 30, 40, 50, 60, and 70 yards. Past 60 yards the diabolos would spiral and the groups would open up a fare amount.

This is not the quickest way to tune an Impact but I enjoyed the process very much and learned a lot about my Impact and diabolo pellets.

Hope this helps.

Troy
Click to expand...
That is awesome how you meticulously were able to work though that to find out exactly what it is that your gun liked! I unfortunately don't have access to any extra air whenever I am at the range.

What made you want to go through that process over some of the other methods that you see online via videos or what others have written about? Just genuinely curious!

Thanks!
 
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Airman is right in terms of how to tune an impact.

- Figure target speed for the pellets/slugs you want to shoot. I am sure other .30 shooters can help with ballpark speeds for given pellets/slugs and reasonable starting pressure to test.
- put macro wheel on 16, micro on 5
- open valve all the way (like 2-3 turns BEYOND line 4
- shoot over chrony and up the regulator in 5 bar increments until you’re ate 103-105% of target speed (e.g., if you want to shoot 880fps you want to go up to 920)
- move micro (not macro!) down in 5-10 click intervals or so (less clicks the closer you get) until you get close to target speed (like 15-20ish fps above), now move it in 2 click intervals until you hit very close to target speed (say 885-890 in the example above)
- now turn valve adjuster in. Half turn intervals at first, then quarter, the 8th and so forth (you may have to go back out at some point if you turn in too far) until your at 880. Done.

Take at least 5 shots after every single adjustment and ignore the first few. Springs need to settle.
 
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hgatesm said:
That is awesome how you meticulously were able to work though that to find out exactly what it is that your gun liked! I unfortunately don't have access to any extra air whenever I am at the range.

What made you want to go through that process over some of the other methods that you see online via videos or what others have written about? Just genuinely curious!

Thanks!
Click to expand...
The physical dimensions and characteristics of both a pellet and liner combination determines the Internal Ballistics which in turn determine the angle (Lateral Throwoff) the pellet will have when it leaves the muzzle. The worse the Internal Ballistics, the worse the Lateral Throwoff the worse the group size.

Increasing velocity, increases spin rate which will increase the Lateral Throwoff.

As such I start pellet testing a liner at very low velocities, as low as 400 FPS, and let the liner physically show me the pellets with poor Internal Ballistics via group size.

A pellet with good Internal Ballistics will physically show me the velocity it is most accurate at via group size.

Testing indoors with no wind means Aerodynamic Jump and Wind Drift are NOT a factor in group size, making Internal Ballistic performance the dominate factor.

I too fell pray to the "pellet of the week & velocity" propaganda and kept testing this "pellet of the week" even though it clearly had the worst Internal Ballistics with my liner and increasing velocity only made it worse, even in the propaganda velocity range.

I never start testing a new pellet outdoors at the propaganda recomended settings for the Air Valve, Macro, Micro, and Velocity because this " pellet of the week" has never been shot from "MY M3" and when shot from "MY M3" it may have the Internal Ballistics of a brick.

Which I want to know before I start trying to accurately throw this brick farther than 20 yards outdoors in the wind and blaming the rifle for my ignorance.
 
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