Impact mk2 losing fps!

[RC_Bladeworks]

Question. I've been having this problem with my mk2 impact (factroy power plenum) in 25 cal slowly dropping fps over a shot string. Usually drops up to 20 fps over a few mags. The first few shots of my current string are around 977 then goes down to 967 after 40 shots and over a few more mags it will go down further. Any ideas?

Btw the tune is good. The first 10 shots have a standard deviation around 1 fps. I can't for the life of me upload a pic here from my smartphone or i could show my shot strings.

 

[spyde82]

Try check your C3 bumber/oring

ore messure the hammer spring adjustment and see if it moves after shooting

 

[8thman]

Did the temperatures drop? I have been loosing 10fps for every 10 degrees, and the difference between the sun and shade because the gun is black makes a difference in my impact mk2 25cal. Hope that helps 

 

[Scotaty]

I have the same problem and I haven't found anything to fix it.

The regulator set pressure slowly decreases with every shot. The difference in bottle pressure 250b to 150b is like 7~9bars. When bottle at 250b the regulator is set at 130, it will go down slowly as pressure in bottle decrease. By the time bottle has 150 bar, regulated air usually go down to 121~123 bars.

 

[GQ]

Check the front valve hammer seat pin. The ideal measurement for this pin is 6 mm visible out of the front of the block.

 

[GQ]

I have the same problem and I haven't found anything to fix it.

The regulator set pressure slowly decreases with every shot. The difference in bottle pressure 250b to 150b is like 7~9bars. When bottle at 250b the regulator is set at 130, it will go down slowly as pressure in bottle decrease. By the time bottle has 150 bar, regulated air usually go down to 121~123 bars.

Ask FX USA and when you got an answer share it with us here please.

 

[azuaro]

RC Bladeworks:

Assuming your gun is mechanical OK (C3 O ring is fine, hammer seat is not loose, etc) then you have a tuning issue...Your gun is shooting at least 8-10% or maybe more below the max velocity that your reg pressure can provide...

In other words: You are using a short (Dwell) high pressure burst of air which is usually very good for accuracy within certain range of the air cylinder fill pressure and the regulator setup...Target shooters (including myself) use this setting (short dwell - high pressure) but REFILL the cylinder way before it reaches the regulator set point...

We usually fill the cylinder to max pressure around 250 BAR and then refill the air cylinder after 30-40 shots to prevent what you are experiencing...People shoot a BR 25 Meter target that has 25 bulls and also shoot an average of 5-15 sighters (40 shots total) and then refill. 

I assume that you want to keep the same velocity that you are shooting, if this is the case then try decreasing the Reg Pressure and increase the hammer pre-load (hammer strike) so the velocity doesn't change (remains as you currently have it set) , this will make the velocity curve flatter and your gun more consistent/efficient...Your issue will be eliminated or at least reduced drastically and you will also notice that the gun will shoot more quietly...I don't anticipate a decrease in accuracy, I believe it will actually increase it or at least leave it as is. 

Best regards,

AZ

 

[GQ]

RC Bladeworks:

Assuming your gun is mechanical OK (C3 O ring is fine, hammer seat is not loose, etc) then you have a tuning issue...Your gun is shooting at least 8-10% or maybe more below the max velocity that your reg pressure can provide...

In other words: You are using a short (Dwell) high pressure burst of air which is usually very good for accuracy within certain range of the air cylinder fill pressure and the regulator setup...Target shooters (including myself) use this setting (short dwell - high pressure) but REFILL the cylinder way before it reaches the regulator set point...

We usually fill the cylinder to max pressure around 250 BAR and then refill the air cylinder after 30-40 shots to prevent what you are experiencing...People shoot a BR 25 Meter target that has 25 bulls and also shoot an average of 5-15 sighters (40 shots total) and then refill. 

I assume that you want to keep the same velocity that you are shooting, if this is the case then try decreasing the Reg Pressure and increase the hammer pre-load (hammer strike) so the velocity doesn't change (remains as you currently have it set) , this will make the velocity curve flatter and your gun more consistent/efficient...Your issue will be eliminated or at least reduced drastically and you will also notice that the gun will shoot more quietly...I don't anticipate a decrease in accuracy, I believe it will actually increase it or at least leave it as is. 

Best regards,

AZ

I agree.