GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: oldpro on February 17, 2016, 10:14:23 PM
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Im going to post some tips and links to help those in need of advise tuning their AG
http://www.calc.sikes.us/1/index.php (http://www.calc.sikes.us/1/index.php)
http://www.airgunsofarizona.com/energycalc.htm?fps=900&grains=55 (http://www.airgunsofarizona.com/energycalc.htm?fps=900&grains=55)
http://www.calc.sikes.us/2/ (http://www.calc.sikes.us/2/)
http://www.airguns.net/calculators.php (http://www.airguns.net/calculators.php)
Now the chronograph I use and Ill explain why shortly
http://www.amazon.com/gp/product/B00HTN5290?keywords=caldwell%20chronograph%20premium%20kit&qid=1455761448&ref_=sr_1_1&sr=8-1 (http://www.amazon.com/gp/product/B00HTN5290?keywords=caldwell%20chronograph%20premium%20kit&qid=1455761448&ref_=sr_1_1&sr=8-1)
And audio cable you will need
http://www.amazon.com/CablesOnline-3-5mm-right-angle-AV-1404R/dp/B00EAON0BI/ref=sr_1_4?ie=UTF8&qid=1456968499&sr=8-4&keywords=3+ring+audio+cable (http://www.amazon.com/CablesOnline-3-5mm-right-angle-AV-1404R/dp/B00EAON0BI/ref=sr_1_4?ie=UTF8&qid=1456968499&sr=8-4&keywords=3+ring+audio+cable)
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First things first and thats setting up your Chronograph. I put mine indoors and shoot it outdoors threw a window in a safe direction into a pellet trap that also holds a standard size target paper. You can get different targets to print for free here= http://www.mytargets.com/ (http://www.mytargets.com/) Now attach light kit to your chronograph and plug it in and remember chronographs hate artifical light so try to avoid it. If your going to data log with the supplied data cable DONT!!! Throw it away and use the cable I listed above or you will get many error or missed readings. Now its time to run a string
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When I run a base string I normally will fill to max fill pressure and shoot the gun down till its going to slow to be useful. I keep this data on my phone where its captured using the data cable from the chronograph, here in the app I can delete or modify the string adding pellet weight or deleting missed shots etc. After I run a base string I normally if more strings are needed will only shoot 1 pellet every 3 shots to conserve pellets until im close. Also remember that when running your string dry fire the first round always its a waste shot that will only screw up your string or misguide you Ill explain why later.
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Ok your chrono is set up with lights on and your ready to run a string so lets run one and see whats going on. Heres a string with a "Korean Cliff" that means its starts real fast and descends rapidly. The cause of this is normally to much hammer strike at the given fill pressure. Two ways to fix this or start to fix it, either fill to a higher pressure if its safe and run again or more likely reduce pre-load on hammer.
Created: 06/10/15 04:16 PM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 0.054
Bullet Weight(gr): 31.00
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
8 906 56.51 28.09
7 917 57.89 28.43
6 930 59.54 28.83
5 940 60.83 29.14
4 945 61.48 29.30
3 953 62.53 29.54
2 971 64.91 30.10
1 977 65.72 30.29
Average: 942.4 FPS
SD: 24.7 FPS
Min: 906 FPS
Max: 977 FPS
Spread: 71 FPS
Shot/sec: 0.1
True MV: 944 FPS
Group Size (in): 0.00
Sent from my iPhone
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What we are after in a non regulated PCP is a smooth BELL CURVE. So what we are after is your starting shot being the same or near the same speed as your last shot in the string with the peek speed in the middle. This will give you the most shots in the target area and the best usage of air. Thus Lower ES and or SD. ES (extreme spread) isn't a total but the difference between the highest & lowest velocity in a string.
SD (standard deviation) is figure showing how close each load is to being alike.
Created: 08/08/15 09:47 AM
Description: bottled Flex .30 non Reg.
Notes 1: 3100 fill to 2400 finish
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 44.75
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
27 881 77.14 39.42
26 885 77.84 39.60
25 888 78.37 39.74
24 895 79.61 40.05
23 896 79.79 40.10
22 899 80.32 40.23
21 901 80.68 40.32
20 903 81.04 40.41
19 905 81.40 40.50
18 909 82.12 40.68
17 907 81.76 40.59
16 906 81.58 40.54
15 908 81.94 40.63
14 903 81.04 40.41
13 910 82.30 40.72
12 903 81.04 40.41
11 910 82.30 40.72
10 907 81.76 40.59
9 904 81.22 40.45
8 907 81.76 40.59
7 903 81.04 40.41
6 900 80.50 40.28
5 ERROR 10
4 896 79.79 40.10
3 896 79.79 40.10
2 893 79.25 39.96
1 888 78.37 39.74
Average: 900.1 FPS
SD: 8.0 FPS
Min: 881 FPS
Max: 910 FPS
Spread: 29 FPS
Shot/sec: 0.1
True MV: 900 FPS
Group Size (in): 0.00
Sent from my iPhone
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Anyone who wants to jump in here is welcome BUT please keep it as simple as possible Im doing this for those with limited tuning knowledge and LESS is more sometimes. You here me BOB LOL and you to Motorhead!!
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Ok lets look at some strings with problems and how I resolved them.
Description: .25 marauder stock reworked valve with SSG .187 barrel port
Notes 1: 2800-1800psi
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 25.40
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
23 895 45.19 22.73
22 889 44.58 22.58
21 891 44.78 22.63
20 890 44.68 22.61
19 916 47.33 23.27
18 891 44.78 22.63
17 906 46.30 23.01
16 908 46.51 23.06
15 908 46.51 23.06
14 912 46.92 23.16
13 912 46.92 23.16
12 903 46.00 22.94
11 903 46.00 22.94
10 910 46.71 23.11
9 895 45.19 22.73
8 912 46.92 23.16
7 898 45.49 22.81
6 887 44.38 22.53
5 909 46.61 23.09
4 888 44.48 22.56
3 883 43.98 22.43
2 900 45.69 22.86
1 903 46.00 22.94
Average: 900.4 FPS
SD: 9.8 FPS
Min: 883 FPS
Max: 916 FPS
Spread: 33 FPS
Shot/sec: 0.1
True MV: 900 FPS
Group Size (in): 0.00
Sent from my iPhone
The above string looks pretty good BUT every once in a while a much faster than normal shot would rear its ugly head!!! What gives? Well the first thing I would check in a string like this is hammer drag or binding. The hammer must flow smoothly down its bore to the valve if we want a string that is consistent. But in this case it wasnt that at all I had mixed two tins ofJsb pellets and some had thin skirts and some thick and when I put in the thin skirt pellet Id get a fst shot. SO when running your strings make sure your pellets do not have bent skirts or are different in any way.
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Thank you Travis for your time and contributions for the benefit of all.
I'm sure many will find this helpful.
(I know I sure will) , subscribed so I wont miss anything you have to teach.
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Ok heres another problem string as you can see it starts off real slow then jumps up quickly. What gives? All air guns have a sweet spot where the valve likes to operate thus fill pressures can make a huge difference when tuning and air rifle and this is the most common cause for inconsistent shot patterns ive seen from customers guns sent in. The above gun was filled to 3K as described by the specs given by the maker( Crosman in this case but as you can see the valve is struggling to over come this pressure and open the valve and not till it dropped low enough in pressure was the pellet able to get up to speed. This gun was so far out of tune I stopped the string early.
Created: 08/14/15 11:38 AM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 141.00
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
5 769 185.18 108.43
4 766 183.74 108.01
3 753 177.55 106.17
2 741 171.94 104.48
1 718 161.43 101.24
Average: 749.4 FPS
SD: 20.8 FPS
Min: 718 FPS
Max: 769 FPS
Spread: 51 FPS
Shot/sec: 0.1
True MV: 749 FPS
Group Size (in): 0.00
Sent from my iPhone
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I had my teaching credentials many years ago and was a 1st Grade teacher many light years ago. Thank you Sir.
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Ok back to business heres another string from a Flex .30 cal and im using a lot of Flex strings only because I have so many with varying results. In this case the Flex has a normal fill pressure of 3K but knowing that higher fill pressures in guns that can be adjusted to open the valve at high fill pressures will yield a tighter ES I filled it to test this out and as you can see at 3500 PSI its very efficient. But this isnt always the case it depends if the hammer energy is strong enough to open the valve at high fill pressures and the valve is able to flow enough. theres a lot more too it but Ill explain more in the advanced course lol.
Created: 07/29/15 01:14 PM
Description: flex 3500 fill
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.50
Ballistic Coefficient: 1.000
Bullet Weight(gr): 44.75
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
8 893 79.25 39.96
7 902 80.86 40.36
6 902 80.86 40.36
5 903 81.04 40.41
4 905 81.40 40.50
3 901 80.68 40.32
2 909 82.12 40.68
1 891 78.90 39.87
Average: 900.8 FPS
SD: 6.0 FPS
Min: 891 FPS
Max: 909 FPS
Spread: 18 FPS
Shot/sec: 0.1
True MV: 901 FPS
Group Size (in): 0.00
Sent from my iPhone
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Hopping on to gain some knowledge. Thanks!
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When the numbers LIE. Sometimes the SD looks fantastic! But the truth isnt always in the SD and ES. Heres another Gun with a Fantastic SD but this gun was set up to shoot 200 Yards and If you look at the numbers you will see To much jumping from shot to shot and at those distances those points between the numbers can mean a complete miss. In this case the gun was shooting slugs and wasnt cleaned well and leading was the issue.
Created: 08/05/15 10:15 AM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 0.540
Bullet Weight(gr): 54.00
Temp: N/A °F
BP: N/A inHg
# FPS FT-LBS PF
8 909 99.09 49.09
7 915 100.40 49.41
6 917 100.84 49.52
5 916 100.62 49.46
4 910 99.31 49.14
3 924 102.39 49.90
2 912 99.75 49.25
1 907 98.66 48.98
Average: 913.8 FPS
SD: 5.4 FPS
Min: 907 FPS
Max: 924 FPS
Spread: 17 FPS
Shot/sec: 0.0
True MV: 914 FPS
Group Size (in): 0.00
Sent from my iPhone
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When it all goes right. Ok you have all your mods done you shot your final string and its as good as you can get it. Sometimes there comes a time when a few points either way just doesnt matter much and you have spent far too much time shooting out into the pellet trap so Its time to call it. Heres a few tunes where I just couldnt eek out another point. I do not sort, weigh or lube my pellets I just dont have time so you will always see some inconsistency due to the pellets themselves.
Description: Flex .30 SSG HFP
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 45.00
Temp: 67 °F
BP: 30.26 inHg
# FPS FT-LBS PF
20 888 78.81 39.96
19 887 78.63 39.92
18 888 78.81 39.96
17 892 79.52 40.14
16 892 79.52 40.14
15 897 80.41 40.37
14 900 80.95 40.50
13 898 80.59 40.41
12 887 78.63 39.92
11 894 79.87 40.23
10 898 80.59 40.41
9 894 79.87 40.23
8 895 80.05 40.28
7 892 79.52 40.14
6 898 80.59 40.41
5 896 80.23 40.32
4 893 79.69 40.19
3 893 79.69 40.19
2 893 79.69 40.19
1 891 79.34 40.10
Average: 893.3 FPS
SD: 3.9 FPS
Min: 887 FPS
Max: 900 FPS
Spread: 13 FPS
Shot/sec: 0.0
True MV: 893 FPS
Group Size (in): 0.00
Sent from my iPhone
Description: Steve
Notes 1:
Notes 2: .22 marauder build
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 0.00
Temp: 68 °F
BP: 30.01 inHg
# FPS FT-LBS PF
42 883 0.00 0.00
41 885 0.00 0.00
40 891 0.00 0.00
39 884 0.00 0.00
38 896 0.00 0.00
37 884 0.00 0.00
36 885 0.00 0.00
35 893 0.00 0.00
34 889 0.00 0.00
33 888 0.00 0.00
32 891 0.00 0.00
31 892 0.00 0.00
30 881 0.00 0.00
29 894 0.00 0.00
28 889 0.00 0.00
27 898 0.00 0.00
26 901 0.00 0.00
25 901 0.00 0.00
24 897 0.00 0.00
23 897 0.00 0.00
22 902 0.00 0.00
21 881 0.00 0.00
20 903 0.00 0.00
19 894 0.00 0.00
18 901 0.00 0.00
17 891 0.00 0.00
16 886 0.00 0.00
15 897 0.00 0.00
14 900 0.00 0.00
13 892 0.00 0.00
12 900 0.00 0.00
11 883 0.00 0.00
10 904 0.00 0.00
9 897 0.00 0.00
8 ERROR 10
7 894 0.00 0.00
6 897 0.00 0.00
5 898 0.00 0.00
4 899 0.00 0.00
3 884 0.00 0.00
2 903 0.00 0.00
1 884 0.00 0.00
Average: 892.9 FPS
SD: 6.9 FPS
Min: 881 FPS
Max: 904 FPS
Spread: 23 FPS
Shot/sec: 0.1
True MV: 893 FPS
Group Size (in): 0.00
Sent from my iPhone
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Now lets use one of those links to learn more about our fine job we did.
http://www.calc.sikes.us/1/index.php (http://www.calc.sikes.us/1/index.php)
Now take the Flex .30 above and put in all the specs with a fill pressure of 3k start and 2600 ending you will now get the efficiency per shot everyone is talking about these days. Now change those fill numbers from 3000psi fill to 2500 psi and you can see how much it changes.
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So what does this all mean? The more efficient you can make your gun the more shots you will get and the more accurate it will be and the report from the muzzle will be the quietest. This is what we strive for and why I stay up to midnight many days a week tyring to find those few points I couldnt find the day before. Im going to dig threw some crazy strings Ive had and see if anyone can figure out what was the problem .
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Ok if you were paying attention than you should be able to tell whats wrong with this tune. ANYBODY dont be shy its a learning experience.
Created: 10/16/14 11:04 AM
Description: WAR carbine
Notes 1: low speed tune HT 7 HS 0
Notes 2: 2900psi to 2400
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 0.00
Temp: 62 °F
BP: 30.05 inHg
# FPS FT-LBS PF
26 761 0.00 0.00
25 764 0.00 0.00
24 765 0.00 0.00
23 757 0.00 0.00
22 742 0.00 0.00
21 742 0.00 0.00
20 739 0.00 0.00
19 727 0.00 0.00
18 723 0.00 0.00
17 716 0.00 0.00
16 706 0.00 0.00
15 704 0.00 0.00
14 700 0.00 0.00
13 697 0.00 0.00
12 696 0.00 0.00
11 691 0.00 0.00
10 684 0.00 0.00
9 676 0.00 0.00
8 671 0.00 0.00
7 665 0.00 0.00
6 666 0.00 0.00
5 661 0.00 0.00
4 654 0.00 0.00
3 646 0.00 0.00
2 643 0.00 0.00
1 636 0.00 0.00
Average: 701.2 FPS
SD: 40.0 FPS
Min: 636 FPS
Max: 765 FPS
Spread: 129 FPS
Shot/sec: 0.1
True MV: 701 FPS
Group Size (in): 0.00
Sent from my iPhone
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Descending velocity right out of the gate ..... YOU NEED A REGULATOR (http://www.bmwlt.com/forums/images/smilies/rofl.gif)
You did say contribute :o
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Butthead LOL
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Butthead LOL
What .... you saying string is ascending in velocity, what was I thinking !!!
You need a regulator !! ... still ;D
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Your not helping... >:(
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Your not helping... >:(
Lol .... but I could ;)
When a set up has velocity INCREASE as pressure within tank is DECREASING .... tells you a few things are in play ???
One being valves poppet is rejecting the opening force exerted by the hammer.
Could be Too Light of a hammer. Too light a hammer spring, TOO HEAVY a poppet spring, Too short of stroke along with a few other reasons. :-\
When one understands the PRESSURE within a given valve on it's own is holding the poppet shut and must be overcome to get valve to lift and flow some air ... understanding this small piece of the puzzle much more comes into focus ;)
As you were TEACHER ;)
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Scott of course is correct and For the less informed heres the fix(normally) You can do one or two things normally but may require both. First increase hammer strike so there is more energy to open said valve at that pressure OR lower fill pressure so less hammer energy is needed to open valve or a combo of both.
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Great thread! I appreciate the easy-to-understand-for-noobs explanations of the adjustments.
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Thanks for this. Love the sites to figure out efficiency and hopefully can tune my guns even alittle better from all this info.
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Ok if you were paying attention than you should be able to tell whats wrong with this tune. ANYBODY dont be shy its a learning experience.
Created: 10/16/14 11:04 AM
Description: WAR carbine
Notes 1: low speed tune HT 7 HS 0
Notes 2: 2900psi to 2400
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 0.00
Temp: 62 °F
BP: 30.05 inHg
# FPS FT-LBS PF
26 761 0.00 0.00
25 764 0.00 0.00
24 765 0.00 0.00
23 757 0.00 0.00
22 742 0.00 0.00
21 742 0.00 0.00
20 739 0.00 0.00
19 727 0.00 0.00
18 723 0.00 0.00
17 716 0.00 0.00
16 706 0.00 0.00
15 704 0.00 0.00
14 700 0.00 0.00
13 697 0.00 0.00
12 696 0.00 0.00
11 691 0.00 0.00
10 684 0.00 0.00
9 676 0.00 0.00
8 671 0.00 0.00
7 665 0.00 0.00
6 666 0.00 0.00
5 661 0.00 0.00
4 654 0.00 0.00
3 646 0.00 0.00
2 643 0.00 0.00
1 636 0.00 0.00
Average: 701.2 FPS
SD: 40.0 FPS
Min: 636 FPS
Max: 765 FPS
Spread: 129 FPS
Shot/sec: 0.1
True MV: 701 FPS
Group Size (in): 0.00
Sent from my iPhone
Valve not able to overcome pressure till late in the string. More preload on hammer spring?
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Exactly you need more preload and possibly a lower fill pressure to boot. Good job! Ill throw some stumpers on in a bit.
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I could have used this a week ago. Oh well learned the long and painful hand pumping way. Still watching in case I need to try something. I can't leave well enough alone sometimes.
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Also remember that when running your string dry fire the first round always its a waste shot that will only screw up your string or misguide you Ill explain why later.
O.K. Obi-Wan Kenobi Luke here, please explain the Jedi Mind Trick, "wasted first shot" as promised.
From what I can tell the PE is the same and the Friction is the same so the KE should be the same. The only thing that has changed since your last shot was the fill pressure and it has come back to where you first started. So why is it a wasted shot??? Is it the Dark side of the Force?
I have seen it always lower but I have no clue as to why.
Thank you. Obi-Wan
Michael :- )
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I was looking at your suggested parts to get and noticed that the audio cable that you listed only has two rings, whereas my Caldwell ballistics chrono cable has three rings. I tried using a two ring cable and it wouldn't make connection. Did u end up using a 2 ring connector cable on yours, or is the one in your link suppose to be a 3 ring?
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Hi it should be a 3 ring Data cable. Same ones that you use for an I Pod.
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Im sorry its this one I will go back and change it http://www.amazon.com/CablesOnline-3-5mm-right-angle-AV-1404R/dp/B00EAON0BI/ref=sr_1_4?ie=UTF8&qid=1456968499&sr=8-4&keywords=3+ring+audio+cable (http://www.amazon.com/CablesOnline-3-5mm-right-angle-AV-1404R/dp/B00EAON0BI/ref=sr_1_4?ie=UTF8&qid=1456968499&sr=8-4&keywords=3+ring+audio+cable)
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Butthead LOL
What .... you saying string is ascending in velocity, what was I thinking !!!
You need a regulator !! ... still ;D
Yes, a regulator would give you more shots at a consistent velocity. My BSA was doing the same thing. I managed to get 70 shots out of it when I regulated it to 18 FPE. Right now it is at 25 and I get 50 shots... but really I should tear it down and set it back to 18 FPE.
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I get this question a lot. Why does my gun shoot slow when I fill higher than xxxPSI? Or why does my ES get huge when I over fill? Well its quite simple really there is a small valve head inside your gun that has pressure pushing it closed and its opened by the hammer when it hits the valve stem. So to open a valve at low pressure requires little hammer energy or how fast the hammer can travel to put it simply. So when you fill to high pressures there is way more pressure in the air tank pushing down on the valve head and requires more hammer energy to open it. Well that sounds ok BUT when you apply enough hammer energy to open the valve at high pressure it then opens the valve a lot at low power where it requires less hammer energy. So most people will have a high pressure tune for higher power shots and a lower fill pressure tune for more consistent shots and a longer shot count.
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MY gun get louder at low pressures??? Well once again this is all about potential energy and valve dwell so let me explain. There is vast more energy at 3K fill then at 2K fill so to push a given pellet to lets say 900FPS at 3k it takes very little dwell or how far the valve opens to get the pellet to speed where as at 2K fill the same speed requires the valve to be held open longer to use more air at a lower PSI to get the pellet to speed this is a long dwell. Long dwell shots waste more air and have the valve open longer thus more report from the barrel. So long dwell low pressure equals loud report and high pressure short dwell low report more of a snap where as a low fill long dwell is more of a woosh.
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Good stuff Travis now I know everything almost sometimes what day is it?? seriously good stuff and thanks for shareing and the lesson. David
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MY gun get louder at low pressures??? Well once again this is all about potential energy and valve dwell so let me explain. There is vast more energy at 3K fill then at 2K fill so to push a given pellet to lets say 900FPS at 3k it takes very little dwell or how far the valve opens to get the pellet to speed where as at 2K fill the same speed requires the valve to be held open longer to use more air at a lower PSI to get the pellet to speed this is a long dwell. Long dwell shots waste more air and have the valve open longer thus more report from the barrel. So long dwell low pressure equals loud report and high pressure short dwell low report more of a snap where as a low fill long dwell is more of a woosh.
I've noticed this when my jkhan bullpup goes off the regulator. I can literally hear when I'm off the regulator because the report sound changes. There is also more of a spring twangy sound after off the regulator. Probably because at that point, I have more hammer energy than needed to open the valve.
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Your right on the money Tim. The valve is being held shut at a constant pressure with the Reg. and when it drops below the Reg. set pressure than you have over dwell = opening the valve to far and to long.
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Also remember that when running your string dry fire the first round always its a waste shot that will only screw up your string or misguide you Ill explain why later.
O.K. Obi-Wan Kenobi Luke here, please explain the Jedi Mind Trick, "wasted first shot" as promised.
I agree, Come on Travis.... You are still teasing us. Inquiring Minds want to know.. LOL
THANK YOU for this thread. Very educational.
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When using loyds PCP Air Efficiency Calculator http://www.calc.sikes.us/1/index.php (http://www.calc.sikes.us/1/index.php) You need to know your tank volume this can be found here for the most common PCPs http://www.airgunsofarizona.com/Tanks/GunVolumes.html (http://www.airgunsofarizona.com/Tanks/GunVolumes.html)
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Also remember that when running your string dry fire the first round always its a waste shot that will only screw up your string or misguide you Ill explain why later.
O.K. Obi-Wan Kenobi Luke here, please explain the Jedi Mind Trick, "wasted first shot" as promised.
I agree, Come on Travis.... You are still teasing us. Inquiring Minds want to know.. LOL
First learn stand, then learn fly. No, seriously, I think I know. I think that it– that it wasn't enough just to want to see Uncle Henry and Auntie Em. And it's that if I ever go looking for my heart's desire again, I won't look any further than my own back yard. Because if it isn't there I never really lost it to begin with. Is that right?
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Hi All,
So I spoke with OBI Wan today. It turns out that when you fill the rifle you generate heat. That heat causes the Poppet to stick. Either because the Poppet not so good because it heated or the Valve seat constricted around the the poppet. Either way throw the first shot out!
Great education for free!
Thanks Travis!
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Another helpful link for ALL your airgun MANUALS. This will save you time looking for all your air gun manuals they are all here in one place. http://www.airventuri.com/site/manuals/ (http://www.airventuri.com/site/manuals/)
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Thanks for the help I like it.
Shane
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Good Stuff!!!
Thanks oldpro!!!
Jim - jhm757
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most folks are familiar with the "SD" calculation yer crony gives..... But their is a better measurement of Deviation that fits us air gunners better: Average Deviation
It tends sot run smaller than SD, but I think its a better reflection of performance than SD. It shows what is yer most likely variance from shot to shot is. Trouble is you 'll need a spreadsheet to calculate it after keying in your string.....
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So Im updating my chronograph in the shop and I thought you all would like to see what Im using now and why. https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph (https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph) and youtube video https://www.youtube.com/watch?v=fVeqTJwmrsY (https://www.youtube.com/watch?v=fVeqTJwmrsY) YES its a bit pricey but you get what you pay for and with its smartphone data logging its as good as it gets.
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Hammer spring. Hey, I keep posting to find someone who tunes break barrels springers; does anybody know somone????
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So Im updating my chronograph in the shop and I thought you all would like to see what Im using now and why. https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph (https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph) and youtube video https://www.youtube.com/watch?v=fVeqTJwmrsY (https://www.youtube.com/watch?v=fVeqTJwmrsY) YES its a bit pricey but you get what you pay for and with its smartphone data logging its as good as it gets.
Nice chrony! Seeing that makes me wonder if it would help typical chronies if they could be mounted upside down on some kind of stand like a saw horse. Maybe get less errors?
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So Im updating my chronograph in the shop and I thought you all would like to see what Im using now and why. https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph (https://www.amazon.com/Caldwell-G2-Ballistic-Precision-Chronograph/dp/B01B7OYNJG/ref=sr_1_1?ie=UTF8&qid=1466720545&sr=8-1&keywords=caldwell+g2+ballistic+precision+chronograph) and youtube video https://www.youtube.com/watch?v=fVeqTJwmrsY (https://www.youtube.com/watch?v=fVeqTJwmrsY) YES its a bit pricey but you get what you pay for and with its smartphone data logging its as good as it gets.
Looks real nice!!
The only thing I see that could be bad is that it would be easier to shoot the chrony by mistake with it on top.
Jim - jhm757
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Just the opposite. Because it doesnt pick up poor lighting there is no need to shoot close to the sensors.
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Just the opposite. Because it doesnt pick up poor lighting there is no need to shoot close to the sensors.
I like the thought of not having to keep the cable on hand to :)
now if I could just trade in my current caldwell chrony for one of these 8)
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Why isn't this pinned in the PCP forum?
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I totally forgot about this thread! I’ll add a little more to it this week.
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Travis, a most wonderfully informative thread! I’ve learned a boat load from you helping me tune my Raptor..many many thanks for the info and your time!
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For moving parts like the bolt and probe (don’t use on hammers) I like krytox Krytox GPL 205 Grease, Pure PFPE/PTFE, 0.5 oz Tube https://www.amazon.com/dp/B00MWLDALQ/ref=cm_sw_r_cp_api_i_-pTeEb8ZQT37S (https://www.amazon.com/dp/B00MWLDALQ/ref=cm_sw_r_cp_api_i_-pTeEb8ZQT37S)
And for bolts that need adjusting but you don’t want to come loose I put a good coat of LET (liquid electrical tape) let it dry completely it drys fast also then install. Bolts like hammer strikers or velocity adjusters etc.
Gardner Bender 07315001126 LTB-400 Liquid Electrical Tape, Easy-on, Waterproof, Indoor/Outdoor Use, 4 Oz. Jar, Black, Bottle https://www.amazon.com/dp/B000FPAN2K/ref=cm_sw_r_cp_api_i_quTeEb8AXG3VK (https://www.amazon.com/dp/B000FPAN2K/ref=cm_sw_r_cp_api_i_quTeEb8AXG3VK)
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Great stuff Travis.
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Here’s another problem child! I see this a lot it’s a common problem you’ll see with power mods etc. Can you tell me what’s causing this high jump in FPS in the middle of the string?
Created: 07/08/19 05:15 PM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 0.00
Temp: 83 °F
BP: 1013.00 inHg
Altitude: 0.00
# FPS FT-LBS PF
30 897 0.00 0.00
29 907 0.00 0.00
28 925 0.00 0.00
27 938 0.00 0.00
26 946 0.00 0.00
25 944 0.00 0.00
24 940 0.00 0.00
23 942 0.00 0.00
22 951 0.00 0.00
21 933 0.00 0.00
20 927 0.00 0.00
19 940 0.00 0.00
18 934 0.00 0.00
17 928 0.00 0.00
16 931 0.00 0.00
15 926 0.00 0.00
14 920 0.00 0.00
13 919 0.00 0.00
12 909 0.00 0.00
11 924 0.00 0.00
10 904 0.00 0.00
9 915 0.00 0.00
8 908 0.00 0.00
7 907 0.00 0.00
6 911 0.00 0.00
5 903 0.00 0.00
4 901 0.00 0.00
3 890 0.00 0.00
2 881 0.00 0.00
1 910 0.00 0.00
Average: 920.4 FPS
SD: 17.8 FPS
Min: 881 FPS
Max: 951 FPS
Spread: 70 FPS
Shot/sec: 0.1
True MV: 920 FPS
Group Size (in): 0.00
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I'll take a stab. To light of a valve spring? Too big t port? I guess thats two guesses.
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I'll take a stab. To light of a valve spring? Too big t port? I guess thats two guesses.
Very good quess!!! But that’s not it. I will however show a string with to light a valve return spring in the future.
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Would this one be too much hammer spring?
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Looks like it has a bell curve of sorts. regulation issue?
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Both good guesses but still not it and it’s a non regulated string.
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I ain't the sharpest knife in the drawer when it comes to reading strings, but it seems like the hammer is sticking a little. There is a lot of variance shot to shot.
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Another good guess but it’s not a mechanical problem. Very common with High power tuning.
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Hmmm I hate problem children lol
Pressure too low for given fpe?
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Hmmm I hate problem children lol
Pressure too low for given fpe?
Not that. Hint, think what mods are common with high power tunes.
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Too heavy of a hammer? I'm not sure. But if it were my gun I'd just turn hammer spring in alittle to get the first shot to start at 920ish fps lol
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Since I dislike "problem children" and also mechanical mysteries Ill keep guessing ;D
Porting over sized?
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Since I dislike "problem children" and also mechanical mysteries Ill keep guessing ;D
Porting over sized?
There ya go! The Transfer port is too large in this case. The valve in this gun has its peak velocity at around 2600 psi so when the valve gets to that point and the big transfer port is not restricting the flow it starts really shooting fast till the pressure drops this sort of over porting will also cause very poor ES/Sd across the board. To fix this you would either tune it for a declining string for hunting or put in a smaller transfer port to slow the flow in the middle power band area and smooth out the string. Very common issue with those seeking Power in their PCP guns.
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Here’s another one what do you think the problem is
Created: 10/16/14 10:10 AM
Description: WAR .25 carbine
Notes 1: 6 turns HT 3 turns HS
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 25.39
Temp: 61 °F
BP: 30.06 inHg
Altitude: 0.00
# FPS FT-LBS PF
16 844 40.17 21.43
15 851 40.84 21.61
14 861 41.80 21.86
13 863 42.00 21.91
12 865 42.19 21.96
11 872 42.88 22.14
10 871 42.78 22.11
9 872 42.88 22.14
8 873 42.97 22.17
7 867 42.39 22.01
6 864 42.09 21.94
5 875 43.17 22.22
4 870 42.68 22.09
3 846 40.36 21.48
2 860 41.70 21.84
1 850 40.74 21.58
Average: 862.8 FPS
SD: 10.0 FPS
Min: 844 FPS
Max: 875 FPS
Spread: 31 FPS
Shot/sec: 0.1
True MV: 863 FPS
Group Size (in): 0.00
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Too much HT?
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Too much HT?
No Sir. Hint This is a mechanical problem
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This is a war .25 carbine so I’m assuming the gun has a bottle on it. To only get that many shots and Have such a short bell curve, the valve is probably over dwelling.
Or if the gun has a small air cylinder. It doesn’t look like a bad string lol.
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Hmmm this is fun...
sticky hammer or greased hammer?
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Hmmm this is fun...
sticky hammer or greased hammer?
This is not a full string I chopped it short due to the issue.Not a hammer issue. This is fun I could do this for months I have 1100 saved strings LOL!!!!
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Im no expert lol but I don't give up easy haha.
How about pellets not being seated past transfer port?
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Im no expert lol but I don't give up easy haha.
How about pellets not being seated past transfer port?
Ow thats a good one and I have a string of that also but not the case here.
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Not consistent pressure from the regulator.
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Is the hammer hanging up on the sear? This is fun and I'm learning a lot. This is tuning 101!
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Fun and challenging. It sure would be easier if the gun was in hand lol
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It might be easier if the gun was in hand but it's a great opportunity to learn how to "read" the velocity data and get a better understanding. I'm really enjoying this thread.
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The nasty ups and downs over the first 6 shots suggest a weak hammer strike relative to the energy level it “wants” to be tuned to. Also, either a weak, broken, or missing valve spring.
The absurd brevity of the bell curve is what bothers me most...unless the pressure vessel is the size of a tangerine.
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Hmmm maybe leak at transfer port?
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In this case it would be easier with the gun in hand but often as a tuner all I get is a string and a collection of thoughts what the customer thinks is wrong with the gun etc. Im trying to make it fun and informative.
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Your doing a good job. This is FUN. ;D
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Hmmm maybe leak at transfer port?
Bingo!!! It blew the transfer port oring and the customer instead of fixing the issue tried to tune around it.
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Yahoo 8) Keep them coming. super fun
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Here’s another one and all the strings I’m posting are non-regulated unless I State it.
Created: 10/29/14 12:35 PM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 27.80
Temp: 77 °F
BP: 30.16 inHg
Altitude: 0.00
# FPS FT-LBS PF
16 895 49.45 24.88
15 900 50.01 25.02
14 906 50.68 25.19
13 908 50.90 25.24
12 912 51.35 25.35
11 930 53.40 25.85
10 922 52.48 25.63
9 919 52.14 25.55
8 930 53.40 25.85
7 923 52.60 25.66
6 939 54.44 26.10
5 929 53.28 25.83
4 942 54.79 26.19
3 936 54.09 26.02
2 934 53.86 25.97
1 928 53.17 25.80
Average: 922.1 FPS
SD: 14.2 FPS
Min: 895 FPS
Max: 942 FPS
Spread: 47 FPS
Shot/sec: 0.1
True MV: 922 FPS
Group Size (in): 0.00
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
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Korean cliff tune with an inconsistent hammer strike.
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Not consistent pressure from the regulator.
Travis already said it's a non regulated rifle.
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Korean cliff tune with an inconsistent hammer strike.
Yes sir to much hammer because it was dragging metal on metal so it became impossible to tune other than a Korean Cliff
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
Well, I don't know about you but for some of us that would be a very very short drive!!! lol
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
Well, I don't know about you but for some of us that would be a very very short drive!!! lol
For some of us(me), it would be a putt!!! ;D
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
Well, I don't know about you but for some of us that would be a very very short drive!!! lol
For some of us(me), it would be a putt!!! ;D
So you're saying you want approach it slowly? lol
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
Well, I don't know about you but for some of us that would be a very very short drive!!! lol
For some of us(me), it would be a putt!!! ;D
So you're saying you want approach it slowly? lol
With a 60 degree wedge!!
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Here’s a tough one! Need a prize for who gets this. I’ll put some hints in if needed
Created: 08/14/15 10:18 AM
Description:
Notes 1: evanix 45
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 141.00
Temp: N/A °F
BP: N/A inHg
Altitude: 0.00
# FPS FT-LBS PF
8 658 135.58 92.78
7 699 153.00 98.56
6 710 157.85 100.11
5 739 171.01 104.20
4 572 102.45 80.65
3 567 100.67 79.95
2 598 111.98 84.32
1 809 204.94 114.07
Average: 669.0 FPS
SD: 86.2 FPS
Min: 567 FPS
Max: 809 FPS
Spread: 242 FPS
Shot/sec: 0.1
True MV: 669 FPS
Group Size (in): 0.00
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I want to punch you right now.
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I want to punch you right now.
Hahahaha!!!
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Here’s my hail Mary.
After shot #1, the valve stem began to push through the poppet, absorbing energy from each successive hammer strike, weakening shots 2 through 4. At shot #5, the stem stopped moving and it began acting normally again.
If instead you tell me it will do this every time you fill to a specific pressure, I’m going to need a cup of coffee.
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Now that is an interesting string!
Is it safe to assume that there are no broken parts in play?
Not to rule out mechanical but just that nothing is broken.
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Now that is an interesting string!
Is it safe to assume that there are no broken parts in play?
Not to rule out mechanical but just that nothing is broken.
Something did fail that’s all I’ll say now
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Plot it. It’s the Big Dipper.
Aliens from another galaxy sabotaged it. Final answer.
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Plot it. It’s the Big Dipper.
Aliens from another galaxy sabotaged it. Final answer.
That’s funny but I doubt many will get the humor
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Hammer spring broke?
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Hammer spring broke?
No but getting warmer
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Broken sear?
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Broken sear?
Nope
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Poppet extruded?
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Broken valve spring.
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Nope none of those
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Striker moving?
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Striker moving?
Very good guess but no. It’s not real elaborate it’s really a simple failure. You’ll all go DUH!!!
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Breech o-ring? That's all I got. 8)
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Not familiar with the gun but maybe another seal somewhere in the path of air?
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Travis, I know how busy you are, but, these strings and solutions would be a GREAT teaching/tuning tool. And a great sticky. Maybe after driving us all nuts with guesses, that would be a possibility?
Well, I don't know about you but for some of us that would be a very very short drive!!! lol
For some of us(me), it would be a putt!!! ;D
So you're saying you want approach it slowly? lol
With a 60 degree wedge!!
Ahh, you're a goffer!! lol Took me a few min. to figure out "60 degree wedge?"
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The stem for the poppet either broke or broke thru the poppet shortening how much the 2nd shot the poppet could open.
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Broken valve spring?
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Breech o-ring? That's all I got. 8)
THATS IT!!! I blew the breech oring on second shot!!!
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Aw, come on >:( You made it sound like it was something off the wall ;D
But let me get this straight, after you blew the breech O-ring on a 200fpe big bore...you just went on shooting? I hope you had earmuffs on!
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It only took off part of the oring and the gun was so loud to begin with I couldnt tell. But It was apparent there was a issue right away.
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Here’s a oddball you will probably not run into ever.
Created: 01/09/19 02:12 PM
Description: SS 2 .25 cal Mrod
Notes 1: 2700 tether poppet 200/352
Notes 2: 1/4 turns
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 34.00
Temp: 59 °F
BP: 29.79 inHg
Altitude: 0.00
# FPS FT-LBS PF
9 932 65.59 31.69
8 561 23.76 19.07
7 420 13.32 14.28
6 446 15.02 15.16
5 403 12.26 13.70
4 336 8.52 11.42
3 302 6.89 10.27
2 283 6.05 9.62
1 255 4.91 8.67
Average: 437.6 FPS
SD: 208.3 FPS
Min: 255 FPS
Max: 932 FPS
Spread: 677 FPS
Shot/sec: 0.1
True MV: 438 FPS
Group Size (in): 0.00
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A piece of debris between the hammer and valve?
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A piece of debris between the hammer and valve?
No Sir
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Ok something seems like its sticking?
Greasy hammer?
Valve seat sticking?
Now i'm going to have to wait for the answer grrrr ;D
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I figure you're playing with a balanced valve when on shot #9, you figure how to make it a dump valve and empty your entire vessel that's acting as a 2700psi tether.
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None of the above
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Hammer lug came loose and tilted at an angle backwards a bit after the first shot.
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I figure you're playing with a balanced valve when on shot #9, you figure how to make it a dump valve and empty your entire vessel that's acting as a 2700psi tether.
On the right track
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Valve stuck open on first shot then settled down.
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I see the 2700 psi tether but......it looks like a nonregulated gun that got filled quite a bit higher than the tune calls for.
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I see the 2700 psi tether but......it looks like a nonregulated gun that got filled quite a bit higher than the tune calls for.
That’s exactly what happened! It was tethered to and external regulator that had a bad gauge reading much lower than the actual fill pressure. Once I figured it out and shut off the tank that’s string is how many shots it took to get to normal speed again. Moral of the story gauges are not always right and when doing work with a new set up verify it with a known good set up.
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I stopped using white Thread sealant tape long ago I found it did a poor job sealing pcp guns for various reasons including balling up during installation and poor slippage between parts while tightening so I started using ptfe gas pipe tape. Like this.
50% less failures with this!
LA-CO 44094 Slic-Tite PTFE Gas Line Pipe Thread Tape, Premium Grade, [260" Length, 1/2" Wide], Yellow https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ (https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ)
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When I have my guns fully assembled I test with leaks with a 1 part dawn dish washing soap 10 parts water mix in a spray gun. I simply spray on all areas of the gun that may leak then wipe down and blow off with compressed air.
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When I have a gun fully assembled and ready to ship or when I’m using it in the field I spray it down and wipe it with SC-1 by Maximus it makes it shine and smells awesome but more importantly it prevents things from sticking to the gun and that’s always a plus.
Maxima 78920-3PK SC1 Clear Coat Silicone Aerosol Spray, 36 fl. oz., 3 Pack Size https://www.amazon.com/dp/B01LY95EFN/ref=cm_sw_r_cp_api_i_B.bfEbSP7AB99 (https://www.amazon.com/dp/B01LY95EFN/ref=cm_sw_r_cp_api_i_B.bfEbSP7AB99)
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I’ve been asked by many people what I use to lube my hammers the answer was and is nothing. I don’t believe in hammer lubes they all fail from either collecting debris or changing viscosity with temperature or absorbing moisture every hammer lube has a weak point. So I either polish the hammer and tube and run it dry or use a MDS hammer that is self lubricating. Never lube hammers ever.
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Sticky valve?
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I stopped using white Thread sealant tape long ago I found it did a poor job sealing pcp guns for various reasons including balling up during installation and poor slippage between parts while tightening so I started using ptfe gas pipe tape. Like this.
50% less failures with this!
LA-CO 44094 Slic-Tite PTFE Gas Line Pipe Thread Tape, Premium Grade, [260" Length, 1/2" Wide], Yellow https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ (https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ)
Oh yes. As someone who has used thousands of feet of teflon tape. I keep it far away from my pcp. Pieces can come off and get stuck in places you don't want lol
The "gas" pipe tape you referenced is WAY better if you must use tape. 8)
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I stopped using white Thread sealant tape long ago I found it did a poor job sealing pcp guns for various reasons including balling up during installation and poor slippage between parts while tightening so I started using ptfe gas pipe tape. Like this.
50% less failures with this!
LA-CO 44094 Slic-Tite PTFE Gas Line Pipe Thread Tape, Premium Grade, [260" Length, 1/2" Wide], Yellow https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ (https://www.amazon.com/dp/B004MYFPAK/ref=cm_sw_r_cp_api_i_d3bfEbB7HTVEJ)
Oh yes. As someone who has used thousands of feet of teflon tape. I keep it far away from my pcp. Pieces can come off and get stuck in places you don't want lol
The "gas" pipe tape you referenced is WAY better if you must use tape. 8)
Also while its obvious to some... The tape needs to be wrapped correctly to have any chance. Wrap in the direction of the threads or it comes of or bunches up.
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So we’ve seen some pretty bad strings and odd ones but how about a really good one and what separates it from a decent string. There’s more to a good string than just the ES let’s get into the basics. So the number one goal for most shooters is to have and accurate gun regardless if the shooter is a hunter or bench rest shooter so to achieve this there are a few things that need to be achieved in the shot string to make this happen. For most people they use the ES or extreme spread this is determined by the fastest shot subtracted by the slowest shot in a shot string. The primary goal is to have a single digit ES when possible when tuning as this will yield the best performance from shot to shot. Now another useful tool is the ES as a percentage and as a percentage you want it under 2% if possible this also is a goal for tuning to get the best possible shot to shot consistency so to get the ES percentage you take the ES divide it by the fastest shot then times it by 100. The last but not least is the SD or standard deviation this is the difference in speed shot to shot it’s not the easiest to quickly figure out that’s why most people use ES or the ES percentage but most chronographs will display the SD but if you want to figure it out on paper here’s a good link.
https://www.mathsisfun.com/data/standard-deviation-formulas.html (https://www.mathsisfun.com/data/standard-deviation-formulas.html)
So below I’ll post a good string then we will go over it using the above tools.
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Created: 12/21/18 03:56 PM
Description: python valve test
Notes 1: 3000-1825
Notes 2: jSB beast diablo
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 16.00
Temp: 44 °F
BP: 30.23 inHg
Altitude: 0.00
# FPS FT-LBS PF
49 799 22.68 12.78
48 800 22.74 12.80
47 799 22.68 12.78
46 800 22.74 12.80
45 799 22.68 12.78
44 801 22.80 12.82
43 802 22.86 12.83
42 801 22.80 12.82
41 799 22.68 12.78
40 801 22.80 12.82
39 799 22.68 12.78
38 801 22.80 12.82
37 802 22.86 12.83
36 799 22.68 12.78
35 798 22.63 12.77
34 800 22.74 12.80
33 801 22.80 12.82
32 801 22.80 12.82
31 800 22.74 12.80
30 800 22.74 12.80
29 801 22.80 12.82
28 798 22.63 12.77
27 802 22.86 12.83
26 801 22.80 12.82
25 801 22.80 12.82
24 798 22.63 12.77
23 799 22.68 12.78
22 799 22.68 12.78
21 802 22.86 12.83
20 803 22.91 12.85
19 799 22.68 12.78
18 800 22.74 12.80
17 804 22.97 12.86
16 799 22.68 12.78
15 799 22.68 12.78
14 801 22.80 12.82
13 801 22.80 12.82
12 798 22.63 12.77
11 801 22.80 12.82
10 798 22.63 12.77
9 799 22.68 12.78
8 800 22.74 12.80
7 801 22.80 12.82
6 799 22.68 12.78
5 799 22.68 12.78
4 799 22.68 12.78
3 798 22.63 12.77
2 802 22.86 12.83
1 802 22.86 12.83
Average: 800.1 FPS
SD: 1.4 FPS
Min: 798 FPS
Max: 804 FPS
Spread: 6 FPS
Shot/sec: 0.1
True MV: 800 FPS
Group Size (in): 0.00
So using this above string let’s look into what makes it desirable as a shooter. First our goal is to have a single digit ES when possible and we do it’s only 6 so mission number one check two we want a ES percentage under 2% so lets check it 6/804x100= .74 or .74% ES that’s very good check box 2 our third goal is the SD remember we want a single digit SD when possible and ours is a outstanding 1.4 check 3.
So to bring it all together to be accurate you need both shot to shot consistently (SD) and consistency over the entire shot string (ES) these two things together will give you the best advantage at hitting your target which is always the primary goal when shooting at something.
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Travis, thank you for creating a thread like this. I'm finding it to be very helpful when it comes to tuning. Do you have a set parameter when it comes to ES? For instance if it is over X amount you take it back to the tuning table and retune it and lower the ES? I know the goal is to get the gun to shoot as consistently as possible but when does it become unacceptable for you?
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Travis, thank you for creating a thread like this. I'm finding it to be very helpful when it comes to tuning. Do you have a set parameter when it comes to ES? For instance if it is over X amount you take it back to the tuning table and retune it and lower the ES? I know the goal is to get the gun to shoot as consistently as possible but when does it become unacceptable for you?
I use a single digit over the entire shot string as my goal it’s not always possible but it’s the goal. So if I have to fill higher or stop shooting lower in the fill to get my single digit that’s what I do. It’s all determined by what the gun does from the first to the last shot to get it to that single digit ES
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That makes sense. Thanks Travis.
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That makes sense. Thanks Travis.
Your Welcome!
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OK Test time!!!
Here’s a string that needs help! You’ve read threw(hopefully) some of the tuning guide and have and idea what to do so now let’s all work together and fix this gun. There’s several ways to fix this so I’ll give you my version after I hear your thoughts.
Created: 10/06/17 11:07 AM
Description:
Notes 1:
Notes 2:
Distance to Chrono(FT): 1.00
Ballistic Coefficient: 1.000
Bullet Weight(gr): 0.00
Temp: 64 °F
BP: 30.26 inHg
Altitude: 0.00
# FPS FT-LBS PF
25 690 0.00 0.00
24 715 0.00 0.00
23 718 0.00 0.00
22 729 0.00 0.00
21 725 0.00 0.00
20 748 0.00 0.00
19 756 0.00 0.00
18 754 0.00 0.00
17 756 0.00 0.00
16 763 0.00 0.00
15 757 0.00 0.00
14 754 0.00 0.00
13 747 0.00 0.00
12 747 0.00 0.00
11 741 0.00 0.00
10 732 0.00 0.00
9 723 0.00 0.00
8 719 0.00 0.00
7 713 0.00 0.00
6 709 0.00 0.00
5 709 0.00 0.00
4 700 0.00 0.00
3 693 0.00 0.00
2 682 0.00 0.00
1 671 0.00 0.00
Average: 726.0 FPS
SD: 26.1 FPS
Min: 671 FPS
Max: 763 FPS
Spread: 92 FPS
Shot/sec: 0.1
True MV: 726 FPS
Group Size (in): 0.00
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Increase HS or lower fill pressure.
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Thanks for this.
1) increase hammer spring tension to cause a "cliff" shot string? or
2) restrict transfer port size?
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What gun? Hammer throw adjustments? What are we working with?
I agree with Pool, choke the t port to flatten it out, add a buffer and lean on the hammer spring a little more.But there's more than one way to skin a cat.
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Good work guys! I strangled the TP and lowered the fill pressure 100 psi then adjusted the hammer strike to accommodate the changes
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Just read thru this entire thread. Thank you, Travis, and looking at the time of your last post, you better hit the sack, lol. It’s almost midnight and you’re holding Airgun tuning class!
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Why isn't this pinned in the PCP forum?
Great general info, would be a good sticky!
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Bump for those who haven't had the chance to read this thread. Lots and lots of good info.
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Bump for those who haven't had the chance to read this thread. Lots and lots of good info.
Thanks Robert! I totally forgot about this!!! Ill throw some current info in this week.
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Well, there's 45 minutes I'll never get back...
I wanted to take a stab at every one of them but I don't have a time machine.... ;)
Thanks Travis, good info.
BTW.... did Jason ever get to punch you?
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I enjoyed this thread a lot when it was going. Hopefully you got some time to continue on with it Travis.
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I enjoyed this thread a lot when it was going. Hopefully you got some time to continue on with it Travis.
To be honest I forgot about it. I’ll tally on. Would you like some short videos also?
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That'd be awesome. These scenarios help out a lot to learning how to diagnose problems and how to fix them.
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That'd be awesome. These scenarios help out a lot to learning how to diagnose problems and how to fix them.
Thats awesome Chris. Im working on a few things to post
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Looking forward to it. Thanks Travis.