Shooting at higher altitudes

[spleify]

I see every once in a while someone will make referance to altitude when shooting. Does it have an impact on how your firearm shoots, or on accuracy?

[trlcavscout]

The difference in pressures at different altitudes will change your POI up/down. As well as humidity and temp.

[KFinn]

Correct me if I'm wrong because I am still in the beginning stages of learning myself.

But specifically, higher altitude = less dense air = less drop and higher velocity at target than lower altitude?

Hotter air and less humidity = similar results as above since the air is easier to cut through

wind seems self explanatory.

[spleify]

Ingteresting, it makes perfectly good sense I just never thought of it.

So, if you site your gun in at 200 yards in the mountains at 10,000 ft, then go some where and you are at sea level your POI will essentially be lower, correct?

Thanks

[Irving]

I was going to ask about available oxygen to feed the explosion, but it seems like since the case is sealed, it wouldn't really be an issue. Maybe less flash though?

[Mtn.man]

If you site in at sea level, and then come to a altitude of say 10k then you will be a smidge high depending on cal., grains, etc. it is not real signifcant at 100 or so yards, but beyond that it can make a difference. Not sure if velocity is a factor. Just going on personal info from shooting up here at 10k+ and then going to FL

[theGinsue]

spleify - Yes, and no. Thr POI will be different, not necessarily lower. There ar a lot of variable to consider. Even if all other options were controlled, to simply state that the change in altitude will cause the POI to be lower" to much too simplified

If you are a big game hunter here in CO, I'm sure that you have heard that, in addition to shooting your hunting rifle throughout the year, you should also try to shoot your rifle at a similar altiude and preferably nearby your actual hunting location.

[trlcavscout]

spleify - Yes, and no. Thr POI will be different, not necessarily lower. There ar a lot of variable to consider. Even if all other options were controlled, to simply state that the change in altitude will cause the POI to be lower" to much too simplified

If you are a big game hunter here in CO, I'm sure that you have heard that, in addition to shooting your hunting rifle throughout the year, you should also try to shoot your rifle at a similar altiude and preferably nearby your actual hunting location.

Exactly. If your sighted for 2k at 80 degrees F and you go hunt at 10k+ and 20 degrees F it could be a big difference, plus other variables like your rifle, the ammo etc. Even if 100yds is your max distance I would check your sights when you get there. I have seen a 2-3" difference just changing a couple k feet and 20 degrees or so even with similar humidity. Also a crosswind will have a different effect in different conditions. And like Ginsue said it doesnt always change the way you think or hope it will.

[funkfool]

I have been looking into this and have found this to help...
http://www.jbmballistics.com/calcula...ulations.shtml
And one (of many suggested) books:
http://www.appliedballisticsllc.com/...files/Book.htm

[Not_A_Llama]

I was going to ask about available oxygen to feed the explosion, but it seems like since the case is sealed, it wouldn't really be an issue. Maybe less flash though?

Gunpowder contains its own oxidizer. Guns work in space - the Soviets had an AA cannon mounted on one of their stations.

Less air density means your bullet is subjected to less drag. It's not a lot, though, until your distances get pretty long.