Tuning .25 600mm M3 tune suggestions??

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Applejackk

Member
Nov 27, 2015
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California, United States
Anyone have tune suggestions for a 600mm .25?! 
Mine is set at 180 first reg, 130 2nd reg, macro on 16 and micro at 4, valve adjuster on the 4th line. But unfortunately I’m still getting ES anywhere from 12-15fps, sometimes even 20. I’ve tried doing a bunch of different things but can’t get the ES down. Shooting 29.5g NSA slugs at around 950fps on power 16, then I dial the wheel to 3 or 4 to shoot pellets. Both the Slugs and pellets are giving me large ES. 
thanks for your help!
 
With the reg setting of 130 bar, what is your maximum FPS with the 29.5 NSA?

With an ES of 12-15fps, I am assuming the 29.5gr will go a bit faster. The closer you are to your maximum fps for given reg pressure, the lower your ES will be.

When lowering the power wheel for pellets, you are getting the pellets to their happy place FPS wise, but a higher ES is to be expected since your firing those pellets way below the MAX fps that pellet could fly at 130 bar reg pressure. Hope that makes sense. I can be bad at explaining stuff sometimes lol.

So if your desired FPS with the NSA 29.5gr is 950fps, lower your reg until the absolute max FPS is between 975-1000fps. Then use your hammer spring adjustment to get you back down to 950fps. That will be you within 3-5% of your max FPS, thus netting you a good ES. Others have figured this out over the years, I'm just passing the info along.
 
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@applejackk - I've seen the same with the M3. You could try lowering the front reg a little bit, see if that helps. TBH, not a huge fan of the front reg on the M3. Mine got fixed by FX after it blew the piston oring, but man, that thing creeps like crazy. I have also replaced the single oring on the adjustment screw.

I've just come to the conclusion that it just won't be as tight as the MK2. Best I can do is about a 9-12ES and still seems to sling slugs fairly accurately. 
 
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With the reg setting of 130 bar, what is your maximum FPS with the 29.5 NSA?

With an ES of 12-15fps, I am assuming the 29.5gr will go a bit faster. The closer you are to your maximum fps for given reg pressure, the lower your ES will be.

When lowering the power wheel for pellets, you are getting the pellets to their happy place FPS wise, but a higher ES is to be expected since your firing those pellets way below the MAX fps that pellet could fly at 130 bar reg pressure. Hope that makes sense. I can be bad at explaining stuff sometimes lol.

So if your desired FPS with the NSA 29.5gr is 950fps, lower your reg until the absolute max FPS is between 975-1000fps. Then use your hammer spring adjustment to get you back down to 950fps. That will be you within 3-5% of your max FPS, thus netting you a good ES. Others have figured this out over the years, I'm just passing the info along.
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Thanks for taking the time to write this. I was going to wait another day before responding as I was spending today trying to tune my M3 to your suggestion. Was gonna give it another stab tomorrow.
At 130bar 2nd reg, valve wide open, and hammer on highest, Im shooting the slugs at around 1000fps. I tried variations of manipulating the valve and/or HS to get it back down to 950fps. No matter what I did, in any order or variations, my ES are as wild as 30fps... over as little as 5 shots! Waiting 10 seconds plus in between. I may be able to take the reg down and achieve the same fps for the 29g slugs, but per AirArmsHunters advice, he prefers a higher plenum reg pressure so the plenum pressure itself closes the valve quicker. Before this tune, I was shooting at 120bar and still getting large ES. This is why I was suspecting my first reg in the other thread you commented on. Im thinking of opening up the 1st reg to match bottle pressure so I can try ruling it out. Not really sure what route to take
 
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ES of 15-20 will not create POI shift even at 100 yards. What’s your goal or trying to kill? Paper or pests?



If you want smallest possible group then you need to find your sweet spot/balance for your reg and HS. Once the sweet spot is found reduce the valve so you scribe another 30fps and that would give you sub 10 ES and SD of 2-3 if your ammo is consistent, NSA slugs are pretty consistent but you still need to weight/sort them if you want sub 2 SD consistently. 


At the end of the day it’s a lot of work to get your ES and SD to BR level but only you can tell if that’s worth the effort or not. I personally like high reg tunes because they are more efficient and quieter but knowing the ES and SD will be a bit higher but I don’t do BR competitions or even enjoy shooting groups. 
 
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ES of 15-20 will not create POI shift even at 100 yards. What’s your goal or trying to kill? Paper or pests?



If you want smallest possible group then you need to find your sweet spot/balance for your reg and HS. Once the sweet spot is found reduce the valve so you scribe another 30fps and that would give you sub 10 ES and SD of 2-3 if your ammo is consistent, NSA slugs are pretty consistent but you still need to weight/sort them if you want sub 2 SD consistently. 


At the end of the day it’s a lot of work to get your ES and SD to BR level but only you can tell if that’s worth the effort or not. I personally like high reg tunes because they are more efficient and quieter but knowing the ES and SD will be a bit higher but I don’t do BR competitions or even enjoy shooting groups.
Click to expand...

This is great. I think it realigned my expectations of what I should be getting. I think I can live with a larger ES. After reading some posts here and seeing that people are getting tiny ES, I assumed thats how they're coming out of the box (especially after paying 2300) and dont realize that it does take a lot of work to achieve such small numbers. Thanks for your help!
 
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