S200 Chronied....
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S200 Chronied....
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Topic: S200 Chronied.... (Read 2390 times))
uncle paulie
GTA Moderator
GTA Senior Contributor
Posts: 4014
Real Name: Paul
S200 Chronied....
«
on:
August 26, 2014, 08:05:11 AM »
Picked up an AA s200 this past spring. Up until this point I have been concentrating on just getting her broken in. After about 2000 shots, I decided to crony it to find the sweet spot in the shot count for FT use. The original setting had it shooting 725 fps with JSB Exacts 8.44. I adjusted the transfer port choke screw to bring up the power to 850 fps. I shot a 60 shot string and the crony results seem a bit weird. Initial charge was 2800psi and was run down to 1800psi.
Most of the strings I see posted start a bit low for a few shots, level off for a good string and then fall off quickly. This string seems to rise fairly rapidly to shot 20, then continues to rise slowly to shot 40 and then tapers off to shot 52 before dropping quickly to shot 60.
I don't have the computer skills to chart or graph the results and am having a tough time analyzing the results to determine the sweet spot.
Any help would be greatly appreciated!
pv
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NJ
gonzav
Marksman
Posts: 333
Shoot as much as often if you can
Real Name: Leo
Re: S200 Chronied....
«
Reply #1 on:
August 26, 2014, 04:50:20 PM »
Paul,
Here is a quick graph chart using your data. I noticed shot 57 was not included in your list.
Hope this helps.
Leo
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USA, Connecticut, Meriden
https://ctairgunners.weebly.com/
TOM aka critter99
USAF Combat Communications ...the best of the worst
Expert
Posts: 1702
"you can agree with me, or you can be wrong" LD
Re: S200 Chronied....
«
Reply #2 on:
August 26, 2014, 08:49:41 PM »
looks like about shots 20 thru 50 will give best ES and SD try about a 2525 psi fill start point and rerun
You want your start pressure to be what it was on about shot 20...or ya can redo string with same fill point stop at shot 20 and check pressure in tube
«
Last Edit: August 26, 2014, 08:51:52 PM by TOM aka critter99
»
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uncle paulie
GTA Moderator
GTA Senior Contributor
Posts: 4014
Real Name: Paul
Re: S200 Chronied....
«
Reply #3 on:
August 27, 2014, 07:25:01 AM »
Without a gauge on the gun i'll have to re-run the string a few times to see if the data is consistent and work from there. I was hoping to find that a some point the plot would flatten-out a bit more. I'm guessing a regulator may be needed to flatten out the string. What a great sport.... every time I buy something- I find I'm wanting to buy something else! Keeps me feeling like a kid waiting for the delivery truck! Ha-Ha!!
pv
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NJ
TOM aka critter99
USAF Combat Communications ...the best of the worst
Expert
Posts: 1702
"you can agree with me, or you can be wrong" LD
Re: S200 Chronied....
«
Reply #4 on:
August 27, 2014, 12:50:42 PM »
if you are tank filling you can tell when valve clicks open at tanks pressure on fill hose gauge
hand pumping ?? its been so long since I hand pumped I don't remember
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Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: S200 Chronied....
«
Reply #5 on:
August 27, 2014, 06:17:45 PM »
Wondering why 13.5 foot pounds?
These guns really seem to run long shot counts in the 12 foot pound range, shot counts seem to shorten disproportionately when pushed past that. You’d think that 10% more energy wouldn’t cost but 10% in shot count, but it often costs more than twice that (more like 20-25%) in shot count.
So you got to one of the ballistic programs and figure out exactly what the difference between starting those 8.4’s at 810fps is going to cost you in drop over 45yards when compared to starting them off at 850 and see if the trade off is worth it to you.
Wrote a long procedure. Then trashed it.
Basically this.
IGNORE VELOCITY at first. Just adjust the striker spring tension until the sweet spot starts at your chosen pressure. Up to you if it is the start of a 4% sweet spot, 3%, or 2%.
Once you get the rifle running in the pressure range of your choice, then play with the transfer port screw to get the velocity/energy you want (with a reminder that very good things seem to happen in the 12 foot pound range).
Set my .177 and .22 versions recently, looking for something about 12 foot pounds for the .177.
Ended up with this (and I’m surprised how well it turned out):
As for pump filling, that's all I've done. The .22 version is 11 years old, and if pump filling has harmned it, I can't find the evidence inside or out.
Ony 122 cc's being filled from about 1600 to about 2600psi, so it's not a lot of work (something like 45-55 pump strokes, depending on the pump.)
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Louisiana
uncle paulie
GTA Moderator
GTA Senior Contributor
Posts: 4014
Real Name: Paul
Re: S200 Chronied....
«
Reply #6 on:
August 27, 2014, 07:44:30 PM »
The reason I began to tweak it was because out of the box I was getting 725fps average(fpe-9.85) with the 8.44's. What I was finding was that at the longer ranges, the wind was a huge factor, hence the desire for more speed which would also help in the trajectory department. Having a graphing program will go a long way to finding that sweet spot. It's one thing to analyze the numbers, but the ability to quickly compare the charts is a big help. I'll back it off and see how it responds in the 12fpe range. New to the pcp world and I have to admit , I like it! I'll post some more results as things develop. Now all I have to do is find some time....
Thanks for the input!
pv
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NJ
Ribbonstone
GTA Senior Contributor
Posts: 12030
Re: S200 Chronied....
«
Reply #7 on:
August 27, 2014, 09:32:45 PM »
Added speed isn't going to help windage much. Windage is based on velocity loss over distance, so starting faster doesn't really help much as the velocity loss is about the same. That added 40fps (from 810 to 850fps) is worth about 1/10th inch in windage at 50 yards. Does a a bit more for elevation, but still a small amount (like less than 1/4").
Now the odd thing about this is that those slower heavier weight (10.3's) are about the same in windage as your faster 8.4's Drop is a good bit different at 50 yards, but the wind plays with them about the same.
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Louisiana
uncle paulie
GTA Moderator
GTA Senior Contributor
Posts: 4014
Real Name: Paul
Re: S200 Chronied....
«
Reply #8 on:
August 28, 2014, 07:49:19 AM »
Would have thought speed and weight would play a bigger part in this. To date haven't done much besides plinking at cans beyond 30 yards and have been surprised at how much drift there is at relatively low wind speeds.
pv
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NJ
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S200 Chronied....