Geographical elevation effect on loads?

[Dubya]

I load & test at 2800 ft. elevation, Should I use a lighter powder load at lower elevation, like 900 ft. and hotter load at higher elevation, like 6,000ft.???
If so, how do you determine what load to use.

Thanks,
Gary.

 

[blawton]

Its just the other way around then you are thinking. But I have seen very little difference in how the gun performs there is just a small change in POI.

 

[Flybuster]

I also do most of my load development and bullet drop testing at long distances at 2800-3000 ft elevation above sea level. I use the same load that I would at the higher elevation when I shoot near sea level, but I just compensate for the drop using my scope adjustments. Ambient temperature seems to play more of an effect on my loads than anything else. But I have noticed I need to put more elevation in at lower levels compared to my normal drops I use in the foothills.

 

[fivering]

Elevation has no effect on Muzzle Velocity. Temperature does.
At higher elevations the air is thinner, with less resistance to the bullet's flight, resulting in less drop.
At lower elevations the thicker air has more resistance to the bullet's flight, resulting in more drop.
Of course humidity also plays a part in the bullet's flight path.
One factor that can be confusing is the angle that the gun is fired in relation to the level.
In the mountains it is easy to be shooting slightly uphill or down hill and not realize it.

 

[clowdis]

I normally shoot Palma rifle (.308 with 155 grain bullets) in North Carolina at an elevation of about 650' above sea level. I have the opportunity once a year to shoot in the Spirit of America matches in Raton, New Mexico which has an elevation of nearly 7,000' above sea level. The same load that shoots at my 1,000 yard zero in NC will shoot 6 minutes high in Raton due to the thinner air. At 300 yards the elevation is about the same. This elevation change is typical of almost all shooters who normally shoot at lower elevations and then go to Raton for the matches there. Flatter shooting cartridges like magnums would probably be effected less.

 

[Dubya]

Thanks to all, I appreciate it.

Gary.