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Effect of altitude and temperature on pellet speed

I had the same problem with my TX 200 with an earlier skirtless Tony Leach kit with Delrin rings.

First day official Chrono was 725 FPS (checked prior to my last lane, We started next to the chrono station, so had to shoot the whole match before finding out if officially we were under 12 FPE). That reading was obtained after 50 shots/2.5 hours in the Arizona heat. I think it's probably heat related.
Was chasing my zero without that chrono information. (if my remember, the gun was shooting 760 FPS during sight-in). Decided to waste three shots during the match to aim at a clean spot and found that POI was high (kinda strange...lower FPS and the POI went up). Guess I don't know my gun that well.

Was unable to sight-in the gun post match first day.

Second day started and I was planning on making changes. Second day sight-in was spot on, so decided against making changes for the 2nd day.
Lost focus on the second day, didn't take my time prior to trigger pull. Plus I think the temp was getting to the Tony Leach kit.

Third day, white course. More of the same. Clean on one lane...mess up next lane...just couldn't get a rhythm going.

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Can't blame the gun or scope. 80% probably shooter related. (position and/or trigger control).
Prior to leaving for Mesa, at sea level, the gun was shooting around 770-780 FPS.
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Came home, stripped the gun. A lot of fine dust. Re-lube the contact/pivot points.
Decided to drop power to 10.5 FPEish. Went with a softer spring.
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Seems to work at the home range when testing. POA=POI proving it wasn't the gun or the scope.
10% misses during the match due to temperature sensitivity for the Tony Leach?
Cos other competitors were running Tony Leach and shot ok. Maybe they made other modifications or were running newer Tony Leach kits.
I know those Delrin rings on my Tony Leach piston can slow the gun down if it's too hot outside. I might be switching to a bronze phosphorus ring per Tony's suggestion.
Still working on position and trigger control
We'll know next match if everything works.

Sometimes, I wished I have never heard of springers.
Congratulations to all those great springers competitors able to shoot over 60% in these challenging conditions (hot, dusty, dry).
Back to the practice range and drawing board for the rest of us.
 
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