I’m routinely traveling between sea level and 8-9000’. Should I be concerned if I charge up a PCP rifle or pistol at sea level and then take it up to a higher altitude?
Thoughts on PCP at higher altitudes
- Thread starter borne2fly
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I"ve never heard anything about differences in elevation on this platform and I have no 'expert' knowledge of it, but here's my thoughts. Air is air. It's thinner at higher altitude which makes for differences in carburetor settings and cooking. Things that use air have to work harder to obtain air than they do at lower elevations. So once you've got it in your PCP bottle, it should be the 'normal' pressure you pressurize it at. No thinner, no thicker. But your compressor/hand pump may make a few more strokes to fill it. The only thing I could think it 'might' affect is a break-barrel? But even then I doubt it would be affected. Just my 2c.
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Traveling between Minnesota and our Colorado cabin at 8800 ft I never noticed any problems. Minor POI shift.
I reside at sea level and pest starlings and ground squirrels @ 4500 feet of elevation and POI is higher than normal due to less air drag, less air at higher elevation = less air molecules slowing the projectile down. And like said above the pressure in your PCP's reservoir remains the same when going from sea level to elevation or vice versa.
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I moved down to about 8500’ from just under 10,000’. Previously lived in Texas at about 800’. Break barrels are DEFINITELY affected by the elevation. Obviously in Texas my break barrels worked like a charm. On top of Conifer mountain they didn’t work reliably at all, now at 8500’ they are marginally better but still disappoint me enough to only use my PCP’s. I regularly run up and down the hill with full tanks and have never had an issue.
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Going up in elevation might affect the pressure in the tank, just a “tad”, because of the less atmosphere pressure on the reservoir, but it would be virtually impossible to measure a difference because one earth atmosphere only has about 33 lbs. of pressure … but like others have said, you’ll get a velocity increase because the air is thinner…
As a side note, I drove truck for a few years and was told that if you had a load of potato chips you would sometimes get rerouted in order to avoid very high altitudes… because sometimes the bags would pop…
As a side note, I drove truck for a few years and was told that if you had a load of potato chips you would sometimes get rerouted in order to avoid very high altitudes… because sometimes the bags would pop…
I believe, and I may be mistaken, that the initial velocity should be the same as the pressure in the plenum will be the same at any altitude as it is a closed system. Now, the velocity at range may change due to the air pressure difference, as has been mentioned, which could result in POI shifts. Correct me if I am not seeing this correctly.
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Mechanically / Pneumatically a Non issue 
Flatness of the shot gets a lot better as the projectiles BC value increases with altitude
Flatness of the shot gets a lot better as the projectiles BC value increases with altitude
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exactly.. I've had a bag pop in my truck cab.. also yes there's pressure change with the tanks as well but it's like you said so miniscule.. you can't even see it on your gauge.. unless you had like one PSI increments.
Mark
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Ok. Seems like the performance might actually improve with altitude. I like that.
Now, if I fill my gear to max pressure at low altitude, is anything going to burst if I take it to high elevations? Never heard of it, but figured I should ask.
Now, if I fill my gear to max pressure at low altitude, is anything going to burst if I take it to high elevations? Never heard of it, but figured I should ask.
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Air is not air as the Density changes and temperature changes with elevation. Do to the steel tank the pressure change won't effect it but the temp change will. I fill my gun in my garage at 62 and 20 minutes later out in the snow I'll have lost 150 psi from the charge being cooled down. Can't say about the shot staying flat as I don't shoot down with the flatlanders.
On a side note, tire pressures drop 2-3 psi and my damn turbos make 3 psi less. On a good note, snow dampens sound and the cold slows it down so I can't hear my wife yelling at me as much. lol. 6,500' el.
On a side note, tire pressures drop 2-3 psi and my damn turbos make 3 psi less. On a good note, snow dampens sound and the cold slows it down so I can't hear my wife yelling at me as much. lol. 6,500' el.
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Sea level pressure is 1 bar or 14.5 psi. So if you went from sea level to space with a PCP the gage wouldn't show any change.
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True, but the pressure differential would change, and that’s the parameter I was concerned about.
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If the PCP is unregulated. A regulated PCP will keep the same pressure as it's vented to the atmosphere pressure.
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Actually that is incorrect. One atmosphere is 14.7 psi at sea level at standard conditions. One atmosphere equivalent of sea water is 33 feet. Thus 33 feet of seawater equals all of the air over your head from sea level to wherever the atmosphere runs out which is essentially called the Karman line at about 62 miles though the atmosphere technically extends to about 6,700 miles. So a diver goes to 33 feet, they will experience 2 atmospheres, at 66 feet three and so on. And an astronaut 6,700 miles above the earth would see pretty much zero atmosphere. I bet a PCP would really shoot nice in space with no worries over ballistic coefficients, could be fun.
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You’re right… I don’t know what I was thinking…I was also wondering how a pcp would shoot in space…that would be cool.
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In Avionics , or Air Planes if you land in the morning in Hawaii the air is cooler , and thicker at noon you can't leave air too thin. The higher you go the thinner the air. That was with small planes not the Jets. Hot air balloons around here in Tucson set off early in the morning as it gets hotter they drop same thing air too thin. Pressure concerns are not going to effect a PCP tank. They by theory should be more powerful In thinner air.
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I see that cause I take out coyotes all the time with my .22 caliber Armada semi-auto. Seems most people think it isn't enough gun. 6,500' el. 30 yard shots.
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