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Location: Utah
Joined: 03/03/2005
Posts: 383
Altitude & Temperature Effects of a Bullet?

I'm a Big Game hunter with a 30-06 and was wondering how much higher a bullet will shoot in higher altitude climates?

I normally sight the 30-06 with 165-gr. bullets in for 200 yards at 4,500 feet above sea level in Utah. This equates to 1.9" high at 100.

When I go hunting in the mountains, the altitude is about 8,000 feet, but a lot colder at 20*F versus 60*F when rifle was sighted in.

So, about how much higher would my bullet be (than 1.9" at 100 yards) with the thinner air at 8,000 feet?

Thanks in advance of your reply!

Steve

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Location: Wa.
Joined: 03/31/2004
Posts: 1300
Altitude & Temperature Effects of a Bullet?

The best thing to do is sight the rifle in the area you plan to hunt.
Don't guess.

Don Fischer's picture
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Location: Antelope, Ore
Joined: 03/24/2005
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Altitude & Temperature Effects of a Bullet?

Here ya go 147 Grain. I got this off my Pact Crono's trajectory calculator.

Using a 165 gr Hornady spire point. I did not enter it's B.C. but rather used the defult in the crono of .380. Hornady claims a max of 2900 fps so that was used. The first time I ran it at 4500' and 60 degrees. then re-ran everything the same but changed it to 8000' and 20 degrees. Used an 8' vital zone and ran it to 300 yds.

4500' @ 60 degrees
B.C. is corrected to .449
max point blank range 316 yds
max point blank zero 269 yds

8000' @ 20 degrees
B.C. is corrected to .473
max point blank range 318 yds
max point blank zero 270 yds

Just a thought, look's like a bunch of hair splliting to me!

Don Fischer's picture
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Location: Antelope, Ore
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Altitude & Temperature Effects of a Bullet?

I should have added;

zero @ 4500' = plus 3.3' @ 200 yds

zero @ 8000' = plus 3.4' @ 200yds

Use the same figure's at 100 yds.

Anonymous
Altitude & Temperature Effects of a Bullet?

147Grain.......It will NOT make enough difference to bat an eyelid over!

It is always good practice to re-zero your rifle in, once you reach the area you are going to be hunting in or around. I worry more about rifle scopes getting bounced off zero than 30 or 40 degrees temperature or elevation change.

Now you will have a lot more to think about, if that buck is suddenly appearing up a slope of say 35 to 60 degrees some 300 yards out in front of you. Those are the things you need to understand and be able to compensate for, come time to pull that trigger on the animal. The same goes if that animal is below you some 30 to 60 degrees and your 200 to 300 yards away.

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Location: Utah
Joined: 03/03/2005
Posts: 383
Altitude & Temperature Effects of a Bullet?

Thanks for the advice!

As for shooting up or downhill, the bullet usually will hit high due to lower gravity - right?

Can you give me an example of about how much higher a bullet might impact when shooting down a 45* slope at 200 yards?

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Location: Wa.
Joined: 03/31/2004
Posts: 1300
Altitude & Temperature Effects of a Bullet?

If you set your rifle so the bullet reaches but, does not exceed 3" high during trajectory. At the point it goes 3" low would be your max point blank range. Approx 280yds. Aim for the center of the target.
Any slight changes in trajectory from angle, altitude, etc. won't need any compensation. You will be in the target out to your max point blank range.

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