My question is if I sight in my rifle, Remington in cal.7MM-08, in Yuma, Az. at an elevation 150' and then go to Colorado to hunt at an elevation of 8500' will the bullet be high or low? I am thinking that it will be higher due to the thinner air and that I should re sight in when I get to Colorado.

Any thoughts on this subject. Thank you.

Yeah, higher, plus you're 8,350 ft. farther from the center of the earth so gravity is less.

Colder temps at elevation may narrow the ballistic efficiency, especially of your ammunition that you gained in the thinner air.

Gravity will increasingly and definitely affect your bullet's flight when shooting over 1200 meters.

Your sight in will be fine, but your bullet will drop Less at distance.

It's always prudent after transit,to gun a zero. Once that is ascertained,it is no thang,to dump the fresh atmosphere in the equation and confirm same,with just a coupla pokes.

Thin air,strips velocity with less authority........................

oldvet -

There are some good apps for cell phones that allow you to control the variables (altitude, temp, velocity, B.C., etc) and provide charts and graphs of trajectory and drift.

There is a free one for Windows (Point Blank) at huntingnut.com that I've used for many year now.Works pretty well and is easy to use. On my Android cell phone I use "Shooter" which also works well. Back when I had an iPhone I used "Ballistic".

There are also quite a few web pages that will allow you to calculate what you need. A google search should provide a good list.

A 100 yard zero is a 100 yard zero whether at 0 feet ASL, or 15,000ft ASL. Provided your scope/rifle hasn’t lost zero.

Past 100 the trajectory will be different however, though slight until past 300.

I live & shoot on my own range at an elevation. 7630'. Can't give you laboratory type drop tables. As you go up in elevation the air is less dense & therefore less air resistance. Breathing here is much more difficult when coming from a lower elevation. Thin air. When I site in my rifle at 100yd for a 200yd zero according to the drop tables in my reloading manual I find I'm dead on at about 235 yds When shooting at my 400yd target I see that I am close to 2" flatter than my drop tables indicate. This will vary with the bullet weight/dia & velocity of your particular . Also allow for a faster time of flight .

I started another thread on this subject. I also see that I am considerably higher impact that what the charts say I should have. Is this a common thing? sight in at about 700' in Michigan, hunting at 5000 in wyoming and 8000 in colorado.

Yes you are correct. Thin air means much less resistance to the bullet in flight. This is like getting a higher BC value on your bullet.. I believe most loading manual drop tables & BC values are related more to sea level This is why if you have Leupold make a custom elevation cam for your scope you need to indicate an elevation range. Sea level drop tables definitely does not work where I live.
When you see many out of state hunters leaving after only 2 or 3 days of hunting due to elevation sickness you then understand how thin the air is. It is very beneficial for out of state hunters to get here in as many days in advance of their hunt as possible to acclimate to the thin air.

A major test was done on a commercial airline a few years ago. They tested flights going east, west, north, south. At an altitude of 38,000 feet, the average adult weighed about a lb less than they did on the ground at sea level, or somewhere around half a percent. Which could also be water lost in a few hours. I appreciate the tongue-in-cheek response though.