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Air temp vs. Pellet speed? FX IMPACT

Air temp slowing pellet?? I would venture to say neglible.

Gun temp slowing pellet? More likely. A cold soaked gun will suffer performance issues, at least from thickened lubricants and (edit...the same volume of air) cold compressed air is at less pressure than hot compressed air.

Altitude density will cause more atmospheric challenges than temperature alone. Altitude density is affected by temperature and humidity together. Dry desert air will drag less than moist swamp air.

Altitude affects are roughly 3% per 1000 feet change. The air at 4000 feet ASL is about 12% less dense than same temp and humidity at sea level.
 
All buy all of that Jim. 

The pellets I use are .25 caliber AirArms weighing 25.4 grains (most are slightly less, ≈.1 to .2 grains) at ≈880 FPS. The listed BC is .036 according to Chairgun. My altitude here in Roswell, is ≈3,500 feet. According to Labradar, the BC is .039 measured when the ambient was about 85°. At 55°, it is .038. I can't attest to the published data or what Labradar comes up with, but it does prove that ambient conditions effect the BC.
 
"JimNM"Air temp slowing pellet?? I would venture to say neglible.

Gun temp slowing pellet? More likely. A cold soaked gun will suffer performance issues, at least from thickened lubricants and cold compressed air is at less pressure than hot compressed air.

Altitude density will cause more atmospheric challenges than temperature alone. Altitude density is affected by temperature and humidity together. Dry desert air will drag less than moist swamp air.

Altitude affects are roughly 3% per 1000 feet change. The air at 4000 feet ASL is about 12% less dense than same temp and humidity at sea level.

so I have some how lost 255fps from my IMPACT, I really didn't think I would lose velocity at them extremes. But I didn't know for sure. 
 
G

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    "Grin_Reaver"Your comment got me thinking would a pcp filled to a 100% recommended pressure at sea level be safe to be taken to 9,000-10,000 ft above sea level? what would be the other considerations for shooting accurately at that altitude if you had zeroed at sea level? sorry for it being off topic.
    
This is why airline dmeand that any pressure vessels be degassed before loading onto the plane.(airgun tube/bottle, air tanks etc.)
     
    I would bet that the safety margins built into our guns would cover an altitude change from Sea level to 10k feet ASL. If anything would be at risk, it SHOULD be a burst disk. I can't swear that all PCP have those ...from a liability standpoint I would be shocked if they did not have them.

    Oxygen is suggested for pilots above 12k and required for pilots above 14k cabin pressure. Cargo holds are often not pressurised and would subject cargo to 28,000 to 35,0000 feet ASL pressure conditions.
     
    Grim... To shoot at vastly different locations, i suggest you take the time to make a new range card. I am not a chair gun users (gasp!) But I do know a few guys who swear by it. 


    A few things I know from living at 4000-8000 feet ASL my whole life...
    The pellet will travel faster at higher altitude...
    The speed of sound is higher
    Solar radiation is much higher.

    Shoot well, be happy
     
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    Your example illustrates altitude density, and I don't argue with that proven science. Often times Phoenix Arizona airport will suspend operations due to altitude density issues.

    To make my earlier posts clear..... Air temperature ALONE is not likely to cause a premium gun (or any other gun) to loose 250 fps per shot.
     
    "JimNM"Your example illustrates altitude density, and I don't argue with that proven science. Often times Phoenix Arizona airport will suspend operations due to altitude density issues.

    To make my earlier posts clear..... Air temperature ALONE is not likely to cause a premium gun (or any other gun) to loose 250 fps per shot.
    
Yeah, there's definitely something else going on in the internals of this gun. That is beyond my knowledge of fixing. I've spoken to a new company that should be up and running next week. There technician is overly qualified and FX Factory trained. I'm hopeful he will finally get this gun where it should have been 2 year's ago.