GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: JohnnyPDX on December 19, 2020, 09:53:54 AM
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I've heard "tune to the knee" many times and now I want to know how. Not looking for more power just reduced ES and long range accuracy.
I have:
Taipan Vet Long .25
factory reg setting as it came from Talon Tunes
chrony
I am reading the rsterne thread and TRYING to digest and arrive at a summary of steps.
https://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0)
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On further reading it seems a PITA if having to adjust the regulator.
"I personally ALWAYS tune my regulated PCPs to the knee of the curve, ie I back off the hammer spring preload until the velocity just starts to drop (3-5% below the plateau is about right).... Generally that extends my shot string 100-200 psi below the setpoint, giving me additional shots on top of the already efficient setup.... If the gun is shooting harder than I want, then I reduce the regulator setpoint a bit, reduce the hammer preload to get back to the (now lower) knee of the curve.... and end up with even more shots.... Yes, I could just back off the preload, but then I have to worry about that bump in the velocity curve below the setpoint, so instead I drop the regulator setpoint and retune to the new knee..."
Source:
https://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=74919.0)
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Here’s the coles notes version.
1 -adjust the hammer spring to get more velocity until there is no gain in speed.
If the speed keeps climbing until you are at coil bind . Your regulator is set too high for the spring. Reduce regulator pressure or get a bigger spring
2-reduce hammer spring tension until you are between 3-5% below max velocity. Call it done.
Now if your velocity is too low or too high. Refer to step one.
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Here’s the coles notes version.
1 -adjust the hammer spring to get more velocity until there is no gain in speed.
If the speed keeps climbing until you are at coil bind . Your regulator is set too high for the spring. Reduce regulator pressure or get a bigger spring
2-reduce hammer spring tension until you are between 3-5% below max velocity. Call it done.
Now if your velocity is too low or too high. Refer to step one.
I am actually laughing right now. I really needed this summary, send me an invoice.
THANK YOU
*This is doable!!!!!!!!!!!!!!
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In my case the velocity keeps climbing until the coil binds so I need to adjust the regulator down but I may not do that I may just back off the hst and see what I get.
Not sure what to do at this point because I'm all I'm really trying to do is adjust for 100 yard shooting and find the best pellet for that and get the lowest extreme spread that I can
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You only need to adjust the regulator pressure if the velocity you get when on the knee is not what you want....
Bob
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I think it doesn't have a knee.
I'm going to do some more strings
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That's an indication the regulator pressure is too high...too high relative to the maximum amount of hammer strike available. You either need to reduce the regulator's setpoint or use a heavier hammer spring.
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That's an indication the regulator pressure is too high...too high relative to the maximum amount of hammer strike available. You either need to reduce the regulator's setpoint or use a heavier hammer spring.
That's what I understand from Hobbyman's simple instructions. Thank God some people know how to condense!
Not sure if I will do that thought it seems pretty straightforward adjusting the reg.
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Sounds like someone is reluctant to tear their gun down to adjust the reg. In the quest for long range accuracy, you must. No shortcuts.
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Or buy a gun with an externally adjustable reg. Now you might understand why they are so appealing.
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Before I take it apart I need to verify that there is even a need to do that.
My verification process is to do cronnie Strings then go shoot and see how it looks on paper
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One chronograph string will tell you all you need to know. If your gun is still increasing speed as you turn the HS adjuster until you can’t cock it, it’s time to degas and get out the tools. Do you know how to degas your Taipan?
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You will need to make one of these.
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One chronograph string will tell you all you need to know. If your gun is still increasing speed as you turn the HS adjuster until you can’t cock it, it’s time to degas and get out the tools. Do you know how to degas your Taipan?
Howdy. I just did a 30 shot string.
low, 922
high, 941
avg, 931
es / range, 20
Yes to this "If your gun is still increasing speed as you turn the HS adjuster until you can’t cock it,"
The Earnest vid showed him degassing by cranking in the hammer spring adjustment screw. Is there a better way?
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In that pic I posted. That little post I built is used to degas. It goes in the back of the hammer. Then you slowly turn the HS adjuster until the gun starts to hiss.
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Then you will have to make something like this to pull your reg out of the tube. Or you can make a reg cannon and blow it out by using your fill probe and some air.
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Or if you have a hand pump you can blow it out. I put a sock over the end then place one foot on the sock and end of the tube couple pumps and bonk right in the sock!
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If this is a project that concerns you, I know jumping online and waiting for answers not worthy. If you feel more comfortable with having instant answers to your questions, send me a PM. I will give you my phone # and you can just text me. I have no major plans today.
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When did s u c k s become a non PC word and have to be replaced with “not worthy”?
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I thought what you wanted to find out is the correlation between hammer spring preload and velocity. This requires shooting a few shots at each hammer spring setting to plot a graph.
Now, if even with the hammer spring backed off all the way, your velocity is higher than you want, then you need a hammer spring with less energy. That could mean a shorter spring. It could mean a lower rate spring.
If the .25 is used for hunting or long range shooting, then the 930 FPS you showed would not seem too much. The variation also seemed like it should be OK. If you want lower velocity; perhaps you just need a heavier pellet :)
Howdy. I just did a 30 shot string.
low, 922
high, 941
avg, 931
es / range, 20
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My ES on my Taipan is like 5fps. I personally like way less than a 20fps spread for shooting at 100yrds. Especially with heavy pellets. It’s there, he just has to go get it.
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When did s u c k s become a non PC word and have to be replaced with “not worthy”?
Overkill on the language controls. I mean to say....that S . U . C . K z
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Perhaps Frank and Johnny would like to declare what pellets they are using. Perhaps a pellet change could narrow the extreme spread all by itself...
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My Taipan is a .22 and it’s on a 22gr slug diet.
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So I'm kinda curious what not worthy and not worthy. I've been removing my Regs from my taipans since 2015.by blowing it out with a hand pump?
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If you go back and read “everything “ in this topic you will see that when I said about having to jump online every time you need answers and have to wait, the words not worthy were magically put in where I said s u c k s. That all. No biggie.
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I think that ES / Range of 20 is reasonable and seriously wonder if a squirrel at 80 yards cares that much but I do wonder what the difference is on paper at 100 yards.
In that 30-shot shot string I started at 200 bar, maybe a squiggle over, so I am gonna shoot from a 240ish fill and see if the results are close. It's too good to bother taking the gun apart. I totally comfortable with a full dismantle and re-assembly but question the return on investment.
One thing for sure... I believe the folks at Taipan are a bajillion % smarter than me and I won't be changing anything besides HS presuure or pellet. The reg change may not be needed. I don't need better mileage so why do I care, I have a ill compressor and Honda generator, air is cheap.
Got sidelined with WORK, easy $80, back at air guns NOW!
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Hades at this point but I believe the best pellet MAY be the JSB 25.4 gr and the FX version of that, we'll see. Used the Hades because I thought i was out of JSB 25.4, wrong, I have another tin.
About "worthy" only has to to with whether I get what I want without taking the gun apart. I love taking air rifleS apart and I may do it this time too. Not a criticism or judgment in ANY WAY.
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This is funny and you guys are AWESOME, ALL OF YOU.
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It all just boils down to what you want out of your gun. If you want to shoot 25gr and can live with a jacked up tune, you are not alone. Many guys do. It “not worthy “ having to take a gun apart, but when you finally get your gun in the zone, you get that monkey off your back every time you are shooting it. A tuned gun feels and sounds nicer too.
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That's a lot of air in your picture I love it
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You inspired me to look at my Taipan notes. Just some general info that might give you something to ponder. Factory tune was 890fps. When I maxed my HS I could get 930 but it was still climbing. So Tony sent me one of his truck springs for my gun. Now with it in, I truly maxed out at 945fps with the reg setting the gun came with. That gun was set 55fps below the plateau. It shot fine but there was definitely room for improvement. The question is, because yours is a .25, does it already have a truck spring in it? If it does and you still can’t reach set point velocity, how high is your reg set. Maybe you know from your shot strings where it’s set. Mine was in the high 120’s. What I found is Taipan gives you just enough spring to make pellet velocity range. I think it’s one of their little secrets to a sweet cocking gun and nice harmonics. I would ask Tony if he put one of his springs in your gun. If not, ask him if his spring will boost a .25. If it does, get it and find out where your gun truly tops out. Back it down 10-15fps and start shooting 33gr pellets. Or take your gun apart and tune it to those 25 grainers.
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You inspired me to look at my Taipan notes. Just some general info that might give you something to ponder. Factory tune was 890fps. When I maxed my HS I could get 930 but it was still climbing. So Tony sent me one of his truck springs for my gun. Now with it in, I truly maxed out at 945fps with the reg setting the gun came with. That gun was set 55fps below the plateau. It shot fine but there was definitely room for improvement. The question is, because yours is a .25, does it already have a truck spring in it? If it does and you still can’t reach set point velocity, how high is your reg set. Maybe you know from your shot strings where it’s set. Mine was in the high 120’s. What I found is Taipan gives you just enough spring to make pellet velocity range. I think it’s one of their little secrets to a sweet cocking gun and nice harmonics. I would ask Tony if he put one of his springs in your gun. If not, ask him if his spring will boost a .25. If it does, get it and find out where your gun truly tops out. Back it down 10-15fps and start shooting 33gr pellets. Or take your gun apart and tune it to those 25 grainers.
A few weeks ago I asked Tony and said the regulator was set at 140bar. I absolutely cannot imagine that he would adjust the regulator prior to shipping, but I do believe he knows what the set point is. Other folks have said their's was set 150. I trust the Tony number.
A 30 shot string starting at 200bar not using the JSB 25.4 is not a valid test... DO OVER with JSB 25.4 at sub 900 closer to 880 and a full string from 245ish to wherever it starts dropping and falling off the reg.
A smaller ES / Range would be cool but I won't change the spring as irt performs nicely right now. More shooting to see truer results.
These are the complete numbers from yesterday. The second column is meters per second. Mr.P kindly made a spreadsheet for me to convert from m/s to f/s. Thank You Mr. P!!!!!!!!!! It would have taken me a half day, or more, to setup a spreadsheet with formulas.
Shot # v (m/s) v (f/s)
1 281 921.91604
2 281 921.91604
3 284 931.75856
4 284 931.75856
5 283 928.47772
6 283 928.47772
7 283 928.47772
8 284 931.75856
9 283 928.47772
10 284 931.75856
11 286 938.32024
12 284 931.75856
13 285 935.0394
14 286 938.32024
15 286 938.32024
16 285 935.0394
17 285 935.0394
18 285 935.0394
19 285 935.0394
20 287 941.60108
21 287 941.60108
22 287 941.60108
23 287 941.60108
24 286 938.32024
25 286 938.32024
26 286 938.32024
27 285 935.0394
28 285 935.0394
29 283 928.47772
30 281 921.91604
28008.53108 total
933.6177027 average
5.759354776 std. dev
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Next time I recommend to continue shooting until the velocity drops further. That will give a better indication of how it's tuned. It looks like it was starting to give a gentle rolloff which suggests your hammer strike is just about right but there's also a subtle but peculiar bell curve thing going on that raises an eyebrow.
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Good Morning Nervoustrigger,
Thank you for analyzing the numbers! Waiting for daylight and I will do as you suggest.
The business of tuning is an interesting one. I had to ask myself "What is my goal" and that was a more difficult question than I first thought.
I want sub moa 100 yard groups.
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Like I said before, if you want sub or even MOA groups at 100, there are no shortcuts. You HAVE to find your max speed for the reg setting, then adjust it to suit your chosen projectile. If you don’t want to take guns apart to achieve an efficient tune, start buying guns that have externally adjustable regs.
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Here's the shot string I did a few hours ago. JSB 25.4 grain, start 235 bar, end 110ish
Shot # v (m/s) v (f/s)
1 283 928.47772
2 266 872.70344
3 280 918.6352
4 266 872.70344
5 278 912.07352
6 266 872.70344
7 278 912.07352
8 266 872.70344
9 264 866.14176
10 276 905.51184
11 266 872.70344
12 263 862.86092
13 278 912.07352
14 268 879.26512
15 266 872.70344
16 267 875.98428
17 267 875.98428
18 267 875.98428
19 266 872.70344
20 266 872.70344
21 267 875.98428
22 268 879.26512
23 267 875.98428
24 272 892.38848
25 267 875.98428
26 268 879.26512
27 270 885.8268
28 275 902.231
29 272 892.38848
30 278 912.07352
31 275 902.231
32 274 898.95016
33 275 902.231
34 275 902.231
35 274 898.95016
36 274 898.95016
37 276 905.51184
38 276 905.51184
39 276 905.51184
40 276 905.51184
41 278 912.07352
42 278 912.07352
43 279 915.35436
44 280 918.6352
45 278 912.07352
46 278 912.07352
47 277 908.79268
48 281 921.91604
49 283 928.47772
50 283 928.47772
51 285 935.0394
52 283 928.47772
53 283 928.47772
54 283 928.47772
55 285 935.0394
56 285 935.0394
57 285 935.0394
58 287 941.60108
59 286 938.32024
60 285 935.0394
54114.17496 sum
901.902916 mean
22.68774731 std dev
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Yes, the rise at the end confirms insufficient hammer strike. The ES suffers as a result.
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Yes, the rise at the end confirms insufficient hammer strike. The ES suffers as a result.
Then I need to turn the reg down since I won't be changing the HS?
I plan on reducing pressure on the belville stack by turning the brass piece on top of the washer by the length pictured as a green line. Does that seem about right for a starting change?
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Spinning the brass piece 180 degrees netted me a 10b change in my set point.
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And remember to use the proper tightening sequence when you put it back together. Start at the bottom tube screws. 1,3 2,4. Move up to the top tube clamp screws. 1,3 2,4. Then the barrel clamp screws. 1,3 2,4.
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Just did the reg adjustment. The Taipan Vet is EASY to work on!
Turned the adjustment 180 CCW (backed it out), we'll see.
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Hope you get results your wanting.
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Hope you get results your wanting.
Me too. It's an adventure and half the fun is getting there.
Merry Christmas
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Right now it's grouping better than ever shooting 34's but I slowed them down.
Full chrony run later but my quick chrony sample indicates low ES. The 34's max out at 820ish fps. Fine.
I may have turned the reg down too far for the 34's but not for 25.4's
Now very confident in adjusting regulator AND not putting it in backwards. ;D ;D ;D
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34's generally run 80-100 fps slower than the 25's. Should be right there for the 25's.
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34's generally run 80-100 fps slower than the 25's. Should be right there for the 25's.
Cool. I set the HS to run JSB 25.4 at 870fps. We'll see how they like that.
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Now you’re talking. Looks like you’ve got it all sorted out and now for the fine tuning. 8) 8)
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Now you’re talking. Looks like you’ve got it all sorted out and now for the fine tuning. 8) 8)
It is looking very good at the moment and I suspect it will stay that way or even get better. You were instrumental in the progress I have made, Thank You!
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I know we have been texting but some of this should be posted here for other people to reference. Now that 918fps is your max, set the gun for 900 and do a little string. Remember to fire 3 shots to let the spring settle after you make an adjustment, then take notes. Adjust up 1/4 turn, fire 3 then do a 10 shot string, go up 1/4 and do it again until you get close to your set point max speed. Then go back and go down from your original setting a couple times. See if your ES gets better or worse at any point. Where ever you finally wind up, then test for accuracy. If you have a tight ES at let’s say 915fps but the gun isn’t accurate, then it’s time to adjust the reg down a smidge. If your ES stays about the same from 880-915fps. Just test all velocities for best accuracy.
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I know we have been texting but some of this should be posted here for other people to reference. Now that 918fps is your max, set the gun for 900 and do a little string. Remember to fire 3 shots to let the spring settle after you make an adjustment, then take notes. Adjust up 1/4 turn, fire 3 then do a 10 shot string, go up 1/4 and do it again until you get close to your set point max speed. Then go back and go down from your original setting a couple times. See if your ES gets better or worse at any point. Where ever you finally wind up, then test for accuracy. If you have a tight ES at let’s say 915fps but the gun isn’t accurate, then it’s time to adjust the reg down a smidge. If your ES stays about the same from 880-915fps. Just test all velocities for best accuracy.
Wow. These are awesome INSTRUCTIONS and I will carefully follow them.
THANK YOU!