FX Valve return, line 4 or 6

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hgatesm

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Oct 1, 2022
41
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Carthage,bTexas, USA
Hello, As you may have seen from my previous posts I am STRUGGLING to get ANY kind of decent accuracy with slugs.

I keep seeing posts, and videos everyone talking about "line 4" on their return valve, the return valve on my gun has 6 lines, which I read in the manual models do come with either 4 or 6,,, there is a huge FPS difference between line 4 and line 6 with everything else being the same.

I was hoping to get some thoughts and opinions on what I should even try, today the best groups that I was able to shoot, I was shooting 43g NSA around 855-860 fps on "line 4"

When I say best groups, I'm still over 2 inches at 30 yards. If anyone would be willing to help, I would greatly appreciate it!
 
hgatesm said:
I'm not sure what c3 is. If its the piece at the end of the valve rod, yes I am certain that it is tight. You also mentioned rubber balls,, the stock valve return I had didn't have any rubber balls. the new spring that I have in there at the moment came with 1 and it looked to be fine when I had everything apart.
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Yep that’s C3. Rubber balls are in there, parts 56 and 57: https://fxairguns.com/wp-content/uploads/2024/10/F11262-Impact-M4.pdf

When you installed the new spring, did you ad the rubber ball that came with it?! If so, that’s your problem. It only goes into m3, not m4 since the m4 already has them. Take it out and you’ll be fine ;)
 
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Slight correction, the part is C1 on the old Impact Mk2 parts diagram and C52 on the M3 diagram. Ernest says in a couple videos it should be close or at 5.5mm, and I know I have heard him say 6mm is ok too. If you screw it all the way down it will change your hammer tension range on your power wheel and alter the total fps range due to the shorter valve rod length.

 
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greenbeans said:
Yep that’s C3. Rubber balls are in there, parts 56 and 57: https://fxairguns.com/wp-content/uploads/2024/10/F11262-Impact-M4.pdf

When you installed the new spring, did you ad the rubber ball that came with it?! If so, that’s your problem. It only goes into m3, not m4 since the m4 already has them. Take it out and you’ll be fine ;)
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Well, that will be an easy fix for tomorrow, at least as far as removing the extra little ball.

I guess I am not sure what the c3 is?
 
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MongooseV8 said:
Slight correction, the part is C1 on the old Impact Mk2 parts diagram and C52 on the M3 diagram. Ernest says in a couple videos it should be close or at 5.5mm, and I know I have heard him say 6mm is ok too. If you screw it all the way down it will change your hammer tension range on your power wheel and alter the total fps range due to the shorter valve rod length.

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Ahhhh okay that is making a little more sense, so on tomorrows list of things I need to buy,, a set of calipers....

So if c3 isn't tight, how is it supposed to stay where it is put?
 
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hgatesm said:
Ahhhh okay that is making a little more sense, so on tomorrows list of things I need to buy,, a set of calipers....

So if c3 isn't tight, how is it supposed to stay where it is put?
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The extra rubber ball is your problem… you’ll see. As for the c3, screw it on until it sticks out 5.5-6mm measured from the block when the valve rod is fully pushed back. I use vibra-tite on mine, others use blue locktite and others don’t use anything so just check whether it is loose when at the 5.5-6mm spec. If it is you’ll need to use something-tite I guess.
 
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Ya'll were correct again! Removed the little rubber ball from the valve spring as suggested in an earlier post and gained a significant amount of FPS, I also got some calipers today, my c3 as mentioned above is at 5.78mm I figured that was good.

I am unable to do any accuracy testing today as the winds are ripping and it would just be counter productive, but I am very eager to see what we got cooking!
 
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hgatesm said:
Ya'll were correct again! Removed the little rubber ball from the valve spring as suggested in an earlier post and gained a significant amount of FPS, I also got some calipers today, my c3 as mentioned above is at 5.78mm I figured that was good.

I am unable to do any accuracy testing today as the winds are ripping and it would just be counter productive, but I am very eager to see what we got cooking!
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Very good then ;) c3 at 5.8mm is perfect. Now you gotta redo your tuning though.
 
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hgatesm said:
Now that I have burned a few hundred dollars in ammo, might actually get some results! However I am completely okay with redoing my tune now that some of this stuff is making more sense.

I would have never have guessed that that little rubber ball would cause that much difference
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The impact is a demanding mistress… but once you know how to play with her she’s lots of fun ;)
 
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hgatesm said:
Thank you all for the information, I got out and shooting this evening with what little daylight that I had. Per the above posts, I swapped out the tungsten hammer for the stock fx hammer.

Slowly started working on setting reg and hammer settings till I maxed those to the point I was not getting any more speed,,, Keep in mind this is at the valve return on 5.

Surprise surprise, accuracy was actually pretty good! At least the best I have had out of any slugs thus far in all of my testing. The big kicker here, was only getting about 840-850 fps. When I tried to increase the valve return towards line 6, accuracy just exited stage left.


Any thoughts??
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you need to go the other way, if your group is getting wider with speed, start closing the valve maybe 1/4 1/8th turns in at a time take 3 shots and repeat you will see the group tighten up, that valve being open that far is wasting air and could be causing an issue.
most accurate way is to measure the valve with calipers from the back of the knob to the block of the gun.
measure your micro adjustment with calipers vs the lines on the side much more accurate.
just have a pen & paper to keep notes. good luck
 
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