FX Impact .25 Chrony Strings Results

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Michael, thanks for posting the comprehensive chrony and shot count test. One question: so the velocity rises from the set 900fps to the 930's (with quite a few shots left) after coming off the 140bar regulator, one may think that the remaining air volume/pressure would be enough for more 900fps shots. I may be wrong(?), but I would assume that the regulator setting could be lowered some while at the same time you could increase the valve opening for more air behind the pellet at that lower regulated pressure to still maintain 900fps. (only for that weight pellet)
 
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I was wondering if you adjusted your power wheel by adjusting the set screw on the cam, before you started shooting, to remove the slop from the MAX setting. Mine is factory set at 18mm (when i checked with a digital caliper), there is a little play when on the MAX setting. I saw Ernest Rowe's video (https://youtu.be/TedxFHkB4Sk) for his 30 cal power wheel adjustment, he adjusted the wheel, so there was no play/slop on the wheel when on the MAX setting. Was not sure if I should leave the adjustment alone before I get started. I'll be shooting both the JSB 25.39 and JSB 33.95. When the snow finally melts, I hope to sight in and figure out the accuracy..Thanks for your insight! - Joe
 
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EliteAirgunr, Thanks for the response! Much appreciated. I was under the impression (per conversation with sales staff) that I should take the slop out of the Power Wheel, and then dial down the power wheel to reduce the speed/increase accuracy of each size pellet. So if I understand you, other barrels 177, 22, and 30 take different Hammer Adjuster settings? So the 18mm factory setting for my 25 cal, is the appropriate MAX setting to have for both the JSB 25.39 and 33.95?; and I could then dial down the power wheel if needed. Thanks for your time - Joe
 
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Only appropriate for the 25.39 which the .25 impact was designed to shoot around. You would need to increase the hammer if you want to shoot the 34gn. The power wheel only needs to be adjusted to shoot the desired pellet at the max speed you want to shoot it at and not too much more if any at all. Otherwise you are just wasting air by having the valve open too long. You can see these effects where Max, 5 and 4 all shoot the same speed. If that is the case in a setup you are just over stroking the reg. 
 
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Quick question guys, had my .25 a few days and not altered anything as yet.
With the wheel on max I’m firing the 25grn JSB’s at 900fps and the 34grn at 810ftps there’s a fair bit of slop in the hammer and the valve is set like this from the factory, does that look right?
Should I take up the slack and wind the valve in a little. 
6f6b31d28ea737b975595a84eb9f5360.jpg
 
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"EliteAirgunr"That valve has nothing to do with slack and what people refer to as taking up the slack. That has to do with your hammer spring.
NO, you should not touch anything or take up any slack if your gun is shooting well. Stop tinkering and work on your fundamentals and learn your holdovers or clicks for your scope. Have fun shooting.
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Yes I understand taking up the slack refers to the hammer spring tension, I just wondered if the valve looked to be wound out a little far, when I read people saying 3 rings showing or 4 rings showing for the valve setting mine looks to be more. 
 
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"Pelletpinger"
"EliteAirgunr"That valve has nothing to do with slack and what people refer to as taking up the slack. That has to do with your hammer spring.
NO, you should not touch anything or take up any slack if your gun is shooting well. Stop tinkering and work on your fundamentals and learn your holdovers or clicks for your scope. Have fun shooting.
Click to expand...
Yes I understand taking up the slack refers to the hammer spring tension, I just wondered if the valve looked to be wound out a little far, when I read people saying 3 rings showing or 4 rings showing for the valve setting mine looks to be more.
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Who setup your gun? Does it group well? Does your shot count fall in line with your caliber? If all those are satisfactory don't touch it. 

Ideally you want to close the valve there until you start to see your fps drop from where you wanted it. Once it drops, open it back up a little till it's right where you want it. This gives you efficiency and doesn't waste air.
 
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Does anyone have any additional information for optimum FPS for the FX Impact .25 w/700mm (any other links or discussions)? Here is a shot string from this afternoon shooting JSB Exact King Diablo 25.39 grains. Happy with performance, but is this too high with the 700mm barrell? With the power wheel turned to “5” I was able to get an average of 935 FPS.



1558558900_20857878925ce5b8b43a04a8.99288080_124C8D00-EB3F-408A-A917-0156219A0F53.png





 
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Guys,

Be sure to watch Ernest's video on tuning the Impact. It really does answer every question on the topic.

Having said that, it doesn't matter how much slack you end up with in the adjuster, how much your valve is open/closed, or what position your power wheel is on. If you follow his procedure, you'll end up in a happy place.

For instance, with my Impact MKII 22 with 700mm barrel, I have the 18gr pellets going 940fps at 95bar, absolute minimum hammer spring tension possible, and valve closed enough to bring velocity down from 1,000fps.

Please watch his video.
 
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I’ve watched his video many times, but it does not really answer my question. I also believe he mentioned a target range that he was tuning down to for a .22 caliber?

There is the manufacturer recommended FPS for each caliber, but also have not seen anything for what that range should be for an Impact equipped with a 700mm barrel.

My FPS increased from 910 to 940 simply changing the barrel, only. The only fine tuning I’ve done is play with the air valve adjuster.

So, is there an ideal range or optimum range when switching from a 600mm barrel to a 700mm barrel?




 
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