30 shot string
Ok a quick note on the string below. We took our scuba tanks to the dive shop to be topped off, we went back two hours later and topped off our gun tanks in the store and then they topped off the scuba tanks once more. In the store I had a full 3K fill in my gun tank at between 65-70 degrees. Out where I did the string it was 50-60 degrees, so take that into consideration. Ok here goes…Starting pressure in between 2900-3000/21.1 Gr. .22 Cal. Beeman Kodiaks/24″ inch barrel/Hi-flo valve.
1. 1040
2. 1068
3. 1065—–Low=1040
4. 1060—–High=1078
5. 1073——Avg=1069
6. 1078—–E.S.=38.20
7. 1073—–S.D.=11.53
8. 1077
9. 1075
10.1076
11. 1078
12. 1071
13. 1073—–Low=1041
14. 1070—–High=1078
15. 1066——Avg=1062
16. 1065——E.S.=37.06
17. 1055——S.D.=12.60
18. 1056
19. 1043
20. 1041
21. 1041
22. 1032
23. 1024——Low=987.5
24. 1021——High=1041
25. 1019——-Avg=1013
26. 1010——-E.S.=53.59
27. 1008——-S.D.=17.37
28. 996.0
29. 994.5
30. 987.5
Well what do you think?
All Replies
‘sam, here is a 20 string done not long ago.
2500 fill
Blod valve and main spring
50 gram hammer
I use spacers so I don’t know what PW
31g Kodiaks.
23inch BSA barrel.
1-946 11-971
2-951 12-977
3-956 13-972
4-955 14-971
5-960 15-969
6-963 16-971
7-971 17-968
8-963 18-963
9-969 19-959
10-973 20-944
AD of 4.5 SD of 9.0
It took me FUCKIN’ AGES to get it tweaked to that 😆
Day to day SD is about 12 😀
Maybe this is where my Blod valve excels? The ability to fine tune it to the point I can get an SD of 4 over 20 odd shots??? 😆
That’s very informative. Am I correct to sum it up as follows?
Hammer LIGHTER IF NECESSARY given no erratic low fps shots and Fill is adequate for 20+ shot strings with a maximum velocity of about 980 fps.
Combining a lighter hammer with higher fill psi only if necessary to achieve a longer flat string of shots.
‘sam has dropped psi to 2550 as anymore pressure than that was putting the pellet too fast. Problem is, he is still using a fluckin’ great hammer thats designed to open a 3000 fill. To calm the big hammer, less preload has been used. Too little preload can effect consistany. (in my experience, the main spring stops giving out its energy consistantly once it reaches a certain point of not enough compression)((yeah, well put Pab! 🙄 )) plus maybe if the hammer isn’t moving fast enough, other variables come into play like frame friction etc. So now, with less fill and too big a hammer, low preload is used and thats why his fps variation is bigger than he’d like. So drop the hammer weight and increase preload again. Shot 1 to 10 say won’t open the valve quite full,shot 10 to 20 is opening the valve fully, and 20 to 25 is using last of effective air. Of course, shot 1 to 10 dropped the tank pressure so when the valve was fully open on 10-20, the pressure was sufficently lower to keep the fps on track.
Its a fine balancing act to find the right pressure, hammer weight and preload to get to that point.
Edit* Though as ‘sam has just pointed out, one string he did with the powerwheel at zero and the consistancy was good, which would eliminate inconsistant hammer strike….
Pab,
That’s very informative. Am I correct to sum it up as follows?
Hammer LIGHTER IF NECESSARY given no erratic low fps shots and Fill is adequate for 20+ shot strings with a maximum velocity of about 980 fps.
Combining a lighter hammer with higher fill psi only if necessary to achieve a longer flat string of shots.
Jerry,
Are my following assumptions in the ball park of what you are doing?
American Condor, shooting 14.5 – 21.1 grain Kodiaks (H&N Barracudas)
or pellet with similar Ballistic Coefficient.
PreLoad (Power Wheel) 2-5 adjusting up to point of NO ERRATIC LOW Velocity Shots.
Fill Pressure to 2450-2650 adjusting for longer flatter strings of shots.
In addition, I’ve seen two different concepts of TOP HAT Adjustments:
1) TH tuned for the Sweet Spot (as described elsewhere) which for some of us is around 0.084-0.086″.
2) TH tuned down to 0.070″ and below, appears to give some the shot count and consistency they require.
For a comparison to the other adjustments can you tell what range your TH adjustment is in?
double post
X2 Jerry. That first string looks like a good working point. Plus you had more shots to do on that string, it wasn’t finished…:lol:
I’d go with those settings, unless you want to start dicking about with a lighter hammer.. As you try to decrease the speed with less preload, inconsistancy becomes more of a factor as the spring is no longer working effectively. You have to have a certain amount of preload to keep the spring doing its thing! That means you then go to a lighter hammer.. I’m betting you got at least 90 odd grams in there.. If it were me, and I wanted to a. drop a bit of speed and b. try for tighter shot to shot, I’d put less hammer in and keep plenty preload. You could go even less psi, but your string could well be shorter then. I would say you want no less than 2500psi (thats prolly about the right psi), and the first few shots not quite opening the valve fully, then top of the curve where the valve is near maxing out, then the downward drop. You need to find about 980 fps when the valve is maxing, then smooth the rest of the string out.I liked that description of the inverted bath tub. Thats what we are really looking for, not a bell. Nice long plateau of tight shots..
But that first string, again if no poi change over the string, is plenty good enough. I wouldn’t be satisfied with that though, simply cos its not tight enough, but were talking personal preference here….
That doesn’t look so bad! The first string looks like a good baseline to tweak off of. I’d try 2400 to start and 5.0 on the wheel and shoot a full 30 shots. It just might be that a 30 shot string comes in a little higher than the goal.
Well I messed with it some more. This was the best I could get. P.W. 5.5 Start press=2450
1. 921.7—Low
2. 944.4
3. 948.7
4.946.3
5. 973.6–Avg=970.5
6. 975.3–E.S.=83.02
7. 990.0–S.D.=28.84
8. 996.9
9. 1003
10. 1004—Hi
11. 1004—LO
12. 1008–Avg=1000
13. 1014—E.S.=11.64
14. 1011—S.D.=3.31
15. 1011
16. 1010
17. 1016—Hi
18. 1010
19. 1007
20. 1012
Start press. 2300
1. 988.2–Lo
2. 997.4
3. 998.4–Avg=1003
4. 1006—E.S.=27.70
5. 1005—S.D.=8.30
6. 997.1
7. 1008
8. 1015—Hi
9. 1013
10. 1008
Start press=2300/End press=2100/P.W.=4
1. 877.9—Lo
2. 893.6—Avg=927.3
3. 909.0–E.S.=82.24
4. 905.7–S.D.=30.19
5. 919.6
6. 940.0
7. 948.2
8. 958.8
9. 960.1—Hi
10. 959.6
Start press=2300/Endpress=2200/P.W.=0.0
1. 630.9=Lo
2. 631.5
3. 636.7–Avg=639.2
4. 635.6–E.S.=20.09
5. 631.3–S.D.=7.48
6. 637.5
7. 643.5
8. 646.5
9. 651.0=Hi
10. 647.1
Just for fun I ran a string using my Talon tank
Start press=2500 P.W.=max and min.=No change
1. 902.9
2. 907.6
3. 904.5
4. 911.7=Hi
5. 907.7–Avg=903.9
6. 902.1–E.S.=15.20
7. 903.3–S.D.=4.12
8. 901.2
9. 900.9
10. 896.5=Lo
Opinions please.
Critter, I use a blod main spring, about 50 grams of hammer and fill to about 2550 psi. Playing around with the spacer(powerwheel) and fill pressure is where you will find the best ‘spot’ for your valve. You don’t need crazy high pressures to achieve what you are after.
No need to post that string but it is good data: it tells you that 2000 at whatever PW it was set to is not enough air for that PW setting……
Ok Jerry. I did do one starting at 2000 but it was on the down side of the curve from the beginning. I’ve been “throwing away” the first shot after every fill.
I finished other 1/2 after awake, but very useful information though 😆
I’ll start posting short instructions at the top so you don’t have to strain to keep up with the why’s and wherefors… 😆
Savagesam,
In addition to the 2500 psi, PW @4 string, shoot another string with a start pressure of 2300 psi and a PW of 1.0. Shoot as many shots as it takes to drop down to the first shot velocity (or second/third shot if they don’t seem consistent).
I feel VERY thankful for their opinions/advice. Keep it coming. I’m the one asking for more.
Every time I read Jerry or Walt thread 1/2 down, I fall in sleep 😆 , it’s too freaking long…..
I finished other 1/2 after awake, but very useful information though 😆
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Lurker,
+1 on everything Pab said. Plus, we advised Sam specifically not to mess with the tophat just yet. Two reasons for that; first, too many variables makes adustment a mess, and second, he started with a good string that he can go back to if he doesn’t like what the other adjustments bring. Yes, he coulud always set the tophat back where it was, but there is risk in damage and the adjustment is at the .001″ level which makes it tougher to replicate than big numbers on a dial. Besides, .069 ought to be enough for the specific goal he had in mind. We can always use the tophat adjustment to fine tune at the end if required.
I’ve seen the low pre-load inconsistency posted enough that I like Pablouk take it seriously. That’s one reason I did not recommend a 0-3 PW setting. I think a polish of the tube and spring and lube with dry graphite might make low PW settings more consistent but I’d prefer settings not requiring perfection…
Anytime you’re tuning a gun like this, it will take some experimentation and fiddling. It’s important to break it into small chunks and not get distracted by looking at combinations that are way out from what we’re after. The first string is pretty good and not far from my initial recommendation. The next string will get us closer to the answer, provided it is at the settings the last string indicated.