Reasonable tuning strategy?

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ArmedLeftist

ArmedLeftist

Member
May 8, 2019
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Colorado, United States
hi, it makes sense to me, to set up my 600 .25 Impact X before tune like this:

1. reg at 150bar

2. adjust set-screw for HST such that all is absolute maximum it can be while still having ability to turn to any of the settings (max-to-min)

3. valve at 3

4. HST turned to some “mid strength” setting

5. Start tuning (pellet FPS, shot count, accuracy/precision) and recording all

6. Adjust as necessary

Seems like most tuning prescriptions start from OEM settings (something less than actual max on HST and 4 on valve). My thought was by maximizing HST from the get-go (and then choosing mid settings on HST and valve)), that the best tune could be found by fine-tuning HST or valve up or down as needed. For me “best tune” is: accurate/precise, max FPE, shot count. In that order.

thoughts?
 




https://youtu.be/9K9uG2KOPt0



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https://youtu.be/9K9uG2KOPt0





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Thanks!
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Actually, that’s the strategy prescription to which I referred which seems to balance FPS and shot-count as the goal, and involves adjusting four different variables. It ends up several minutes into it, about where I’m proposing to start (thereby taking out the variable that is the unknown OEM HST “max” (arguably the most “involved” variable to change)). From then on, for any given reg-pressure, all tweaks done just by adjusting the wheel and the valve. As the background to all that, my priority is on Accuracy and FPE downrange, THEN tuning for reasonable shot-count. 
 
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I would follow Ernest video, but also you have to shoot on target for accuracy when you start to finetune the last step, which he also say in the video. You may not end up exactly like 20fps lower than maxspeed. On my last tune my goal was 830 fps. When the max speed with a given repressure was 850fps, the gun was not that accurate until I lowered the speed to 810fps. So I see the 20fps difference more like a minimum to not waste to much air, but for accuracy you may have to have bigger difference.
 
Upvote 0
I would follow Ernest video, but also you have to shoot on target for accuracy when you start to finetune the last step, which he also say in the video. You may not end up exactly like 20fps lower than maxspeed. On my last tune my goal was 830 fps. When the max speed with a given repressure was 850fps, the gun was not that accurate until I lowered the speed to 810fps. So I see the 20fps difference more like a minimum to not waste to much air, but for accuracy you may have to have bigger difference.
Click to expand...

Thanks. How did you initially decide that 830fps was your “goal”? Seems a person wouldn’t yet know any specific numbers as starting out “goals”, but would let the process reveal the numbers (where simply “maximum accuracy with maximum power” would be the goal), 
 
Upvote 0
I would follow Ernest video, but also you have to shoot on target for accuracy when you start to finetune the last step, which he also say in the video. You may not end up exactly like 20fps lower than maxspeed. On my last tune my goal was 830 fps. When the max speed with a given repressure was 850fps, the gun was not that accurate until I lowered the speed to 810fps. So I see the 20fps difference more like a minimum to not waste to much air, but for accuracy you may have to have bigger difference.
Click to expand...

Thanks. How did you initially decide that 830fps was your “goal”? Seems a person wouldn’t yet know any specific numbers as starting out “goals”, but would let the process reveal the numbers (where simply “maximum accuracy with maximum power” )would be the goal
Click to expand...

Oh yeah. My additional thought was thst by maximizing full possible HST from the getgo and then "working" from the middle of the wheel and the valve that i might have usable quick-adjust under and over-head to accommodate pellets with more or less weight. Ill be the first to admit i might be missing something fundamental here. Seems to me that Earnest method tunes for the bench. I am trying to tune for hunting. 

I am tuning an unregulated prod today for the same use. Maybe ill discover that I'm missing something
 
Upvote 0
I would follow Ernest video, but also you have to shoot on target for accuracy when you start to finetune the last step, which he also say in the video. You may not end up exactly like 20fps lower than maxspeed. On my last tune my goal was 830 fps. When the max speed with a given repressure was 850fps, the gun was not that accurate until I lowered the speed to 810fps. So I see the 20fps difference more like a minimum to not waste to much air, but for accuracy you may have to have bigger difference.
Click to expand...

Thanks. How did you initially decide that 830fps was your “goal”? Seems a person wouldn’t yet know any specific numbers as starting out “goals”, but would let the process reveal the numbers (where simply “maximum accuracy with maximum power” would be the goal),
Click to expand...

The .25 barrel on my gun is rather new, and it seems to foul up with lead rather quickly. I am not found of having to clean the barrel with less than 200 or 100 shots trough it. I have read somewhere that if you have problems with lead fouling it helps to keep the speed of the pellets moderate. I have also added some silicone oil on the pellets. It helps but the groups still wander a litle. So for the time being my plan is to just shoot some thousands of pellets trough the barrel, and see if it gets better. The added shot count is also nice in that regard as I do not have to go and fill my divebottle as often. I also mostly do target shooting, and some say the pellets actually drift less in the wind than going beyond 900fps. So for me going beyond 900fps might not be nescesarry for my use. I will probably at some point later increase the speed, just because I can:)
 
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Seems to have worked pretty well so far

Set HST to 2 (set to 18.1mm OEM “Max” setting), 130bar on reg, and dialed for FPS drop (3 on valve) for efficiency.

1020fps with GOT pellets (ran out of JSB Exact). Good groupings (.50 cent piece) at 30yds, but hope to get tighter with a few more tweaks. Hoping lead Exacts will group tighter.

Turning wheel to max, shooting 34gn NSA slugs, get much tighter groupings at same POI. Approx 780fps.

Exact Kings on way. Interesting to see what happens. 
 
Upvote 0
I would follow Ernest video, but also you have to shoot on target for accuracy when you start to finetune the last step, which he also say in the video. You may not end up exactly like 20fps lower than maxspeed. On my last tune my goal was 830 fps. When the max speed with a given repressure was 850fps, the gun was not that accurate until I lowered the speed to 810fps. So I see the 20fps difference more like a minimum to not waste to much air, but for accuracy you may have to have bigger difference.
Click to expand...

Thanks. How did you initially decide that 830fps was your “goal”? Seems a person wouldn’t yet know any specific numbers as starting out “goals”, but would let the process reveal the numbers (where simply “maximum accuracy with maximum power” )would be the goal
Click to expand...

Oh yeah. My additional thought was thst by maximizing full possible HST from the getgo and then "working" from the middle of the wheel and the valve that i might have usable quick-adjust under and over-head to accommodate pellets with more or less weight. Ill be the first to admit i might be missing something fundamental here. Seems to me that Earnest method tunes for the bench. I am trying to tune for hunting. 

I am tuning an unregulated prod today for the same use. Maybe ill discover that I'm missing something
Click to expand...

It does not matter if you tune for bench, or hunting. The velocity or power, you deside for yourself
 
Upvote 0
Thanks. How did you initially decide that 830fps was your “goal”? Seems a person wouldn’t yet know any specific numbers as starting out “goals”, but would let the process reveal the numbers (where simply “maximum accuracy with maximum power” would be the goal),
Click to expand...
Click to expand...

A good place to start IMO is first figuring out what it is you expect out of it. High shot count? Long range? High power? Low power?

For me, I want long range accuracy. What I have found is that environmental factors play a huge part (wind especially), so for me that means using ammo with a good BC and finding the velocity that is optimal for the ammo. 

If you determine that your requirements are shooting under 100y, then you have a lot of flexibility. If you're trying to shoot accurately beyond - then you'll want to find the highest BC ammo that you can shoot, that can give you close to your required shot count as possible - and then find the optimal max speed that doesn't cause drift when the projectile comes close to the transonic drag / drag coefficient "spike" as it approaches Mach 1. 

Heres a rough example DC of what the ammo I'm shooting looks like with the various drag laws applied:

1559058378_7203494435ced57ca93c433.39189278_3B1CC469-C863-4D91-9B5B-A4C03D621AD5.png

 
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