Impact M3 valve fully open, goes much more than 1.5 turn past marking 4

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nerijus

Member
Nov 27, 2021
21
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Kaunas, Lithuania
Hi. Manual says that M3 valve is fully open when it is 1.5 turn from marking 4.
On my .22 M3 Sniper it actually goes more, like 3 or even 4 full turns.
I was tuning my gun for 34 gr H&N slugs and found out that valve 1.5 turn gives me something like 800 fps, but I get max on 4 full turns - 950 fps. It just does not go any further because reaches the shroud.
The gun is stock with no modifications. 1st reg 170, 2nd reg 140 bar, macro 16, micro 5

Is it ok to have Valve that much opened?
At first I had constant shots, but after some 50 shots the speed was dropping by 20-30 fps.

Before the slugs the gun was tuned for JSB monster pellets 25 gr. And the valve was at marking 4. I was pushing JSB pellets at 914 pfs. (1st reg 150, 2nd 85bar) But now when I tried with pellet after playing with slugs I do not get the previous speed, it dropped far below 900fps. I had to open valve much more to get the previous speed, 3 full turns past marking 4.

Why did this happen, did I ruin something?

Thanks for help.
 
There is also a possibility that the spring is out of place being that it was opened so far I would pull the barrel and take the valve adjuster check the spring to make sure it isnt damaged and put it back in place my guess is that it came off the c1 and is no longer in the right spot making you open the valve adjuster more I would check it out before doing any more shooting my bad shouldn't need to pull the barrel just unscrew the shroud
 
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Airgunmann said:
There is also a possibility that the spring is out of place being that it was opened so far I would pull the barrel and take the valve adjuster check the spring to make sure it isnt damaged and put it back in place my guess is that it came off the c1 and is no longer in the right spot making you open the valve adjuster more I would check it out before doing any more shooting my bad shouldn't need to pull the barrel just unscrew the shroud
Click to expand...
My bad does not make any sense, the correct way to say it is my bag. Check it out and you will see that I am correct.
 
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Several good comments here. If the C1 is unscrewing, it will take more hammer travel and/or dwell time for the valve opening to achieve previous speeds.

Also, if you increase reg pressure, you may need more hammer weight or spring power to open the valve.

Being that you seem to be chasing a previously achieved velocity without changing any internals or reg settings, my guess would be the c1 isn't maintaining its seating depth.

Do you feel any air coming out by your cheek? If so, you could have a blown oring on the end of the valve rod.
 
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7Green said:
Several good comments here. If the C1 is unscrewing, it will take more hammer travel and/or dwell time for the valve opening to achieve previous speeds.

Also, if you increase reg pressure, you may need more hammer weight or spring power to open the valve.

Being that you seem to be chasing a previously achieved velocity without changing any internals or reg settings, my guess would be the c1 isn't maintaining its seating depth.

Do you feel any air coming out by your cheek? If so, you could have a blown oring on the end of the valve rod.
Click to expand...
Hi,
I do understand that changing the reg preasure, hammer has to be changed accordingly. Reg 85, macro 3. Reg 140, macro 16. I will check c1 later today. What i found out now is that the the smaller ball in valve regulator is deformed, its not in the shape of ball any more... So the explanation could be the c1, if it is going too far.
Do you know if it is safe to operate hammer on max having valve at lets say marking 4? Could it be that hammer striking max, the pin travels too far and can already deform the ball in valve adjuster?
I do not feel the leak.
 
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At what reg pressure (2nd reg) were you previously seeing your highest speeds?

If you simply adjusted you reg pressure up and set your macro and micro dials to there max, you may have went past the max capabilities of your hammer and spring combo. Meaning you may need either a heavier hammer, a stronger spring, or both in order to get more energy out of the hammer assembly and open the valve at higher pressures. I dealt with this a lot in my 35 cal testing.

It you just randomly lost velocity at the same settings as before with no reg changes, I would think the c1 loosening, an oring, or a spring issue.
 
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7Green said:
At what reg pressure (2nd reg) were you previously seeing your highest speeds?

If you simply adjusted you reg pressure up and set your macro and micro dials to there max, you may have went past the max capabilities of your hammer and spring combo. Meaning you may need either a heavier hammer, a stronger spring, or both in order to get more energy out of the hammer assembly and open the valve at higher pressures. I dealt with this a lot in my 35 cal testing.

It you just randomly lost velocity at the same settings as before with no reg changes, I would think the c1 loosening, an oring, or a spring issue.
Click to expand...
Looks like I have the answer. c1 is loos, the measurement is 8.3 mm. And if I am right it would be equivalent to 2 full turns.
I will have to loctite it.
And as I mentioned before the smaller ball is deformed, will need to order a new one ... it's in the shape of a flat 2 mm washer now. Would there be more comments on modifying it like in the video here, I found it on the other thread:
 
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