1st shot string, OK?
How do these numbers look to you guys? I know that many shoot heavier pellets. Should i crank up power wheel or will this just waste air with little gains and more noise? I will say accuracy is outstanding in my small backyard at 20 meters, love this rifle!
Bone stock TSS at factory settings
2400psi – 15.8 JSB Diablo Exact – 4.5 on power adjuster – 12” barrel
1 – 771.8 – 20.9037 FPE
2 – 774.3 – 21.0393
3 – 768.2
4 – 769.2
5 – 765.3
6 – 768.0
7 – 765.4
8 – 762.9
9 – 760.0
10 – 755.8 – 20.046 FPE
How to (cheaply) measure PSI at end of string?
Mike
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Viewing 6 replies - 1 through 6 (of 6 total)
I noticed that so wondered if I could guestimate that way.
I found the Top Hat post in another forum. I’m going to read everything and pick up some blue loc-tite.
Thanks for the info!
Mike
Mike when you refill your gun tank watch the gauge on the SCUBA tank closely..It will rise quickly until it gets to the gun tank pressure and then slow down…At the psi that it slows will be your ending gun tank pressure….
Thanks guys.. I had a feeling that crank it up would be the option:)
The 2400 psi is where new gun came in the mail;) I will also do a string at 2K where I plan to re-fill, then another string at 2.8k to see where factory settings shoot.
I have only the new style AF tank fill for SCUBA. This works very well compared to my Disco filler. However Scuba pressure will only push open top hat when SCUBA pressure is greater than gun tank.
I guess I would need to find an adapter, like the hand pump valve, with a guage to read remaining gun tank pressure after shot strings?
The top hat is flush with top of valve stem so I should use the blue loc tight at this position?
THX,
Mike
yep, take the tank up to 2800psi–use a tiny dab of blue locktite on the two small set screws on the top hat- snugg them well—-with the fill pressure being higher you may want to turn up the preload up to 5.5 or so– your string may start now higher in the 700s and steadily swing up thru the sweet 800s or so —poi shouldnt change much—I shoot .20cal currently 18″—from a 200bar fill with my hand pump—13.5 jsbs start at 850 -by shot 7 or so they hit 900-918 and stay there over 30 shots—–that particular pellet averages 900 fps in mine 😀 –pw7—- if you were really happy with your first string-just you bring everything up a level === it will knock your sox off… 8)——–try some 14.3 jsbs in your gun —run strings –you may be able to squeeze more shots out -by using less air at equal or less preload same fill pressures- and generate damn near the same muzzle energy-by way of higher velocity-and have a quicker barrel time to boot-increasing accuracy ——–from a 2900psi fill 30 shots later mine is usually right at 2600psi— thats at power wheel setting of 7….just some thoughts no real answers…sorry…
2 things to add Mike. Looks like you could afford to increase
the fill pressure some to take full advantage of the shot count….
Your string should start low, increase to a point and then start
to decrease in FPS…It looks like 2,400psi fill is putting you right
at the middle of the Bell power curve….
The cheap way to check
ending psi is to hook the tank to the pump and watch the gauge.
When you feel the resistance on the pump increase and you see
the gauge needle slow to a crawl when pumping that is your ending psi…..String looks good.
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Mike …Do Not tighten the screws on the top hat too much…Just lightly snug….they will bend the air valve tube and the top hat will not turn anymore if you need to adjust it….