Altitude and it’s effect on load development?

[Pdvdh]

Your exterior ballistics will change but interior will not. You want to keep your zero at the 100 yards range so you have less issues and you will certainly need to shoot some before hunting with that kind change. I hunt from 6500 ft to 9000 ft here in Mt.

If the temperature is identical at 1,900' El, 6500' El, 9000' El, and any other elevation on planet earth, your bullets will leave the muzzle of your rifle at the same velocity.

The ballistic trajectory of the bullets leaving the muzzle will be different due to the less dense atmosphere at higher elevations.

Just added a little more description to what bigngreen posted.

 

[Rick Richard]

So are you saying just rezero my rifle when I get there? Should it shoot the same or will it change the accuracy? Also can I just rerun the ballistics from my dropnchart at home and change the altitude and be good don't think I would really be shooting over 300-400 yards.

At those distances, I would not be concerned at all. However, if you are just make the PREDICTION in any ballistic calculator and you can see what the difference is. Then, you can set zero for those anticipated conditions. Good luck!

 

[Pdvdh]

Agree. At 300-400yds, don't worry on large game sized animals. If you're shooting at field mice, better rezero your rifle at the different altitude.

 

[FIGJAM]

@Rick Richard And yet you tried to define ethical distance for the OP with your comment about the materiality of the differences in altitude. Slippery slope on a long range hunting website. I thought this site was supposed to be a safe place for long range hunters without lectures on ethics or somebody trying to define the ethical range an animal should be shot?

All I did was show some numbers as evidence that is can be a material difference depending on how far you are shooting. 1000 yard shot on deer or elk isn't a stretch on this site.

 

[Rick Richard]

@Rick Richard And yet you tried to define ethical distance for the OP with your comment about the materiality of the differences in altitude. Slippery slope on a long range hunting website. I thought this site was supposed to be a safe place for long range hunters without lectures on ethics or somebody trying to define the ethical range an animal should be shot?

All I did was show some numbers as evidence that is can be a material difference depending on how far you are shooting. 1000 yard shot on deer or elk isn't a stretch on this site.

Ok, but the OP also mentioned his max distance of 300 - 400 yards. So, really altitude does not make a difference when shooting deer/elk side game.

 

[FIGJAM]

Ok, but the OP also mentioned his max distance of 300 - 400 yards. So, really altitude does not make a difference when shooting deer/elk side game.

You are right, but that was after your comment...

 

[SilverbulletMAG]

As others have already mentioned, it does make a difference but shouldn't be so much of a difference that it causes you to miss if you were otherwise dialed in. As you go higher in altitude, you get the equivalent of a higher BC bullet so, if you're shooting longer ranges, you will want to take all of that into account. Plenty of ballistic calculators out there that will allow you to enter altitude/atmospheric conditions and plot out the differences.
From my own experience, I routinely shoot at 9k elevation and have all of my rifles zeroed at that altitude. I head to MN for whitetail hunting every year and when I re-verify my zero upon arrival, I'm always 1/2"-1" low (depending on caliber) shooting at the lower elevation. Other conditions come into play of course (temp, barometric pressure, etc) but I know to expect that slight drop. Inside 300 yards though, not a big deal.

 

[Trnelson]

There is a sticky thread in the Bullets, Barrels and Ballistics sub-forum that covers this topic in depth. Take a peek
https://www.longrangehunting.com/threads/altitude-vs-barometric-pressure.11950/

 

[tankgijohn72]

ok I have been thinking about this. I live in ND were our altitude is around 1900-2000. Now if I'm to go on an elk hunt in Idaho, Wyoming, Montana and end up hunting at higher elevation how will that affect my loads? Won't it change velocity which means my rifle and load wouldn't be in tune to each other anymore?

I do all of my load development at about 1500 feet elevation. I zero the rifle at 300 yds at 1500 ft. When going out west at 6500-10,000 ft, I had to dial my scope down 1/4 moa and I was in the center at 300. This was shooting 129 barnes lrx out of a .270 win. I have repeated this process with a .35 whelen (zeroed at 200 yds), a .300 WM, and a 26 nosler. You shouldn't see a drastic shift in zero when gaining altitude. Check zero at altitude and start hunting. Your drop/windage at extended ranges will change quite a bit when gaining/losing a lot of altitude and you will need to account for it.