FX Impact M3 Tuning Advice (inconsistency)

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Floridaman2005

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Oct 11, 2024
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So I have my Impact shooting pretty decent groups after tuning but most of my shot charts look like this. I am shooting 18.1g FX ammo at 120/85 bar and usually shoot between 880-900 fps.

I did notice my regs creep a little and that’s why the first shot is low, but why the buildup like that. Should I have more pressure at the rear reg so it has a stronger contact with the valve adjuster? I can’t figure out why my strings are like this. Anything I can fix?


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Here ya go:

FX - FX impact M4 velocity “warm up”

I’m wondering if someone can shed some light on this question. I’ve recently got an FX Impact M4 .22 700mm with slug power kit installed, heavy liner, carbon sleeve etc. If the rifle has been resting (but is room temperature) I notice it takes a good 10-15 shots for the velocity to get to...
www.airgunnation.com www.airgunnation.com
 
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Floridaman2005 said:
It’s a 500mm
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I was going to say low, I think he's having to open the valve too long to get the velocity. For Giggles I'd go up another 10 bar or so and start reducing his hammer/dwell. I'd also increase #1 to 140 faster refill. We don't see hit shot timing and with low pressure that'll play havoc with speeds...JMHO
 
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Floridaman2005 said:
So I have my Impact shooting pretty decent groups after tuning but most of my shot charts look like this. I am shooting 18.1g FX ammo at 120/85 bar and usually shoot between 880-900 fps.

I did notice my regs creep a little and that’s why the first shot is low, but why the buildup like that. Should I have more pressure at the rear reg so it has a stronger contact with the valve adjuster? I can’t figure out why my strings are like this. Anything I can fix?


View attachment 514956

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I can accept that 20+ FPS spread for a regulated airgun which cost s$300.
For an airgun that cost $2000+ not so much.

A $2000+ airgun better be almost perfect.
As in I can shoot it without tuning it.
 
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nobody1 said:
I can accept that 20+ FPS spread for a regulated airgun which cost s$300.
For an airgun that cost $2000+ not so much.

A $2000+ airgun better be almost perfect.
As in I can shoot it without tuning it.
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Well I’ve shot most groups with spreads around 5. This was after letting the gun sit for a few days and the first 20 shots of the day on it. The low first shots were due to a little reg creep but it took a little while before it leveled off. It’s definitely not tuned to perfection as this is my first PCP and first tune attempt. That’s why I came here for advice.
 
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Floridaman2005 said:
Well I’ve shot most groups with spreads around 5. This was after letting the gun sit for a few days and the first 20 shots of the day on it. The low first shots were due to a little reg creep but it took a little while before it leveled off. It’s definitely not tuned to perfection as this is my first PCP and first tune attempt. That’s why I came here for advice.
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It takes one shot with every other gun on the planet to clear what happens when your reg creeps a little. What you are experiencing is not your fault.
 
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Vetmx said:
It takes one shot with every other gun on the planet to clear what happens when your reg creeps a little. What you are experiencing is not your fault.
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It’s really not worth making a big deal over that the first 2 shots of the day come out 10-15 too slow. A dry fire before shooting would essentially eliminate the issue. And it really has never affected accuracy. It really doesn’t both me at all and there are multiple fixes out there from polishing the piston to buying a new Huma reg. If I was worried about $ I would have bought a cheap rifle. If I need to modify my regs to be more precise or pay for an “upgraded” part, so be it. I’m happy to learn the inner workings of the rifle and spend some time getting things ironed out. Love everything about the rifle. Hard to complain about 1/2 shots being off. I’ll never be in a situation where I can’t dry fire a shot before loading a magazine.
 
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You’re absolutely right it’ll probably work itself out, but I still think you’re using too high pressure. Maybe you need to play with the hammer a little more will you get about 30 ft./s faster than you want and then start lowering the rec pressure about 5 pounds at a time Until you get to 900 ft./s then start playing a little bit with the bow return adjustment until you get both consistency and even better accuracy but the reason no hurry you’ll get it exactly what you want by the time you’re done I have no doubt and you’ll get used to the gun as well so in my book, it’s a win-win situation
 
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1handwill.gc said:
You’re absolutely right it’ll probably work itself out, but I still think you’re using too high pressure. Maybe you need to play with the hammer a little more will you get about 30 ft./s faster than you want and then start lowering the rec pressure about 5 pounds at a time Until you get to 900 ft./s then start playing a little bit with the bow return adjustment until you get both consistency and even better accuracy but the reason no hurry you’ll get it exactly what you want by the time you’re done I have no doubt and you’ll get used to the gun as well so in my book, it’s a win-win situation
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Agree with the reg pressure speculation. But I'd start with a lower pressure and slowly raise it until you get your sweet spot.
Raising the pressure as you tune is soooo much easier than lowering it when tuning.
 
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dens228 said:
Agree with the reg pressure speculation. But I'd start with a lower pressure and slowly raise it until you get your sweet spot.
Raising the pressure as you tune is soooo much easier than lowering it when tuning.
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I definitely started on the low side from what I understand about the compact barrel. I looked up a lot of tunes and stumbled upon a video of someone on here, his name slips my mind, but it was all about impact m3 compact .22 tuning and I copied his first 18.1g tune. And I got very similar results someone suggested turning UP my first reg to 140 for better refresh rate and increase my 2nd. I’ve adjusted both but haven’t had a chance to test the results. Also curious to see how the pellet port will affect things. I have used slug port since day 1 because that’s how it was when I bought it but when I took it apart to clean it I swapped to pellet port to see if that is better since I’m shooting pellets. I’m happy to try different things and see what works.
 
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Chukar60 said:
Up your 2nd reg setting and back off the hammer spring.
With that short barrel you need a short air burst.
Best way to accomplish that is higher plenum pressure and less hammer strike. The plenum pressure will close the valve faster if it is higher and low plenum pressure allows the hammer to open the valve farther than needed.
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Don’t I need to be at the “knee”? If I up the 2nd reg to say 110 and then dialed the hammer spring back, aren’t I not tuning to peak efficiency? Aren’t you supposed to almost max out the hammer and then dial back with the valve adjuster and that is what limits the valve open time?
 
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Floridaman2005 said:
Don’t I need to be at the “knee”? If I up the 2nd reg to say 110 and then dialed the hammer spring back, aren’t I not tuning to peak efficiency? Aren’t you supposed to almost max out the hammer and then dial back with the valve adjuster and that is what limits the valve open time?
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Put the valve at 4 and leave it there until IF/AND WHEN you need some fine tuning.
You put the 2nd reg at 100 or whatever and slowly increase the hammer until your fps starts going up. I'd start the hammer micro at around 2.5 or a bit more. If FPS stop going up and you aren't at your desired speed you raise the 2nd reg, put the hammer back at 2. 5 or so and do it again. When your speed maxes out with the hammer adjustment about 5-10% higher than your goal lower the hammer back down until your at your desired speed. Some may do that until your about 10 fps above your desired speed and then turn the valve in a tiny bit at a time until the speed drops to what they're looking for.
 
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