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.

[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.

[edjobsman]

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?

I remember doing an experiment in chemistry lab were we burned this chemical in air. The big surprise for many of us was that the resulting compound was heavier, a lot heavier than the starting chemical. That means that a weigh-able amount of O2 combined with the chemical resulting in an oxide.

Here is the part that I don't have any data on: I don't know how much the O2 weighs in a given cartridge and I don't know how much O2 would be required for a chemical reaction involving gun powder, if any. There can't be much O2 in the cartridge; I would guess not enough to power a chemical reaction powerful enough to fire a bullet 100s of yards. I can't imagine being able to weigh the cartridge O2 even with a very sensitive analytical balance and a method to do so. Therefore my guess is the oxidizer is not in the air in the cartridge, but rather in the powder itself or it gets sucked in down the barrel as the bullet comes out, which doesn't seem right because I think the reaction would be too slow (have you ever poured smokeless powder on the ground and lit it?) and might interfere with the forward motion of the bullet. Also if it were atmospheric oxygen, I bet there would be a lot more ash or soot (like the stuff we weighd in the cubicle in the lab) after the reaction. That would equal a lot dirty barrels. I realize that the air pressure caused by the "burning" powder might blast some of the dirt out if enough pressure could be generated. What's in gun powder? Sulfur, charcoal, salt peter (Capt. Kirk's recipe). I bet one of those is supplier of oxygen.

Sorry - verbiage. Hey I like to write...