Tuning Mk 2 impact shot string tuning

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Kahoona

Kahoona

Member
Aug 10, 2019
8
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Mn, United States
I don't understand this I have not made any changes this is over a 3 day period the pressure on the reg is 110 bar never shot below 210 bar and always started at 250 bar 33.5 nsa slugs and the groups match the irratic speeds all over the place nothing is any ideas?
Screenshot_20210725-195129_FX Radar.1627261029.jpg

 
My gut feeling is that with 935 on 110 bar with 33.5gr you are overdriving the reg. In other words not tuned well. I would back the valve adjustment out to fourth line and with PW set to max, find the max velocity for the current set point while adjusting the HS adjustment and not adding more HS than is needed. Once you know the max, adjust the valve knob in to drop the max by 5 %. Stop at line one and use HS adjustment if more drop is needed. This is the most efficient the reg can run at that set point. If you want a different speed, readjust the reg and go again.
 
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I'm with triggertreat, looks like it's unbalanced a little bit. I'd expect the reg to be more around lower to mid 120s. Then you won't be smacking the poo out of it with the hammer either. Key point in what TT said is do it with the valve turned all the way out and target about 5-7% over where you want to be from a final fps standpoint. I then back the valve in until I start to see a slight drop in fps and then back the hammer down til I reach my target. 

Results in a very balanced tune with consistent speeds.

Screenshot_20210627-194225_FX Radar.1627314958.jpg

 
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I'm trying what was said 

I backed the hammer spring out

turned the reg to about 125

and left the valve on the 4th line

Changed the batteries on the chronograph 

I also found my set screw that seats the transfer port was loose and the barrel was 1/16 out (probably my accuracy issue)

And the first few shots were so slow it wouldn't register on the chronograph so I started turning in the hammer spring until I got to 850 fps and now I'm walking it up a 1/4 turn at a time. I think from what I've read from others I should be between 900 and 920 fps depending on accuracy does this sound correct? 
 
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I'm trying what was said 

I backed the hammer spring out

turned the reg to about 125

and left the valve on the 4th line

Changed the batteries on the chronograph 

I also found my set screw that seats the transfer port was loose and the barrel was 1/16 out (probably my accuracy issue)

And the first few shots were so slow it wouldn't register on the chronograph so I started turning in the hammer spring until I got to 850 fps and now I'm walking it up a 1/4 turn at a time. I think from what I've read from others I should be between 900 and 920 fps depending on accuracy does this sound correct?
Click to expand...

That speed range has been good for me, but so has many others. It just depends on the goal you are trying to reach and the accuracy you are able to achieve within that desired goal.
 
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