Elevation effects on bullet trajectory

Moose1878

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We are preparing for a mule deer and antelope hunt. Our home shooting range is approximately 3200 ft elevation, and the hunt area averages 6300 ft. My question is how much will the elevation change affect point of impact. Rifles will be zeroed at 200 yds.
 
I can't tell you the exact effects other than I used a 100 yd zero and coupled with my Kestrel 5700 elite, I had no issues hitting out to 700 (farthest target) on my last venture in Montana. Using a 100 yd zero minimizes the environmental effects. I did calibrate my Kestrel at the range in Montana that was about 7,000' elevation. I live at sea level in Florida. If I remember right it took me a lil less MOA to hit at the same distance.
 
If you have ballistic app go in and "play" with elevation changes in whatever form you work with and understand. If needed you should be able to setup a "test" rifle with your matching data if you don't want to change your original data. I always use station pressure myself. Also along with elevation try humidity and temperature changes to see what influence they may change for you. Hope this helps , good luck on your hunt.
 
May differ greatly, may not differ at all, may hit lower which is counter to what most see depending on conditions at your zero location vs hunting location. Density altitude is something to look into at both your zero location and hunting location. Elevation alone is not what matters, it's a combination of elevation (atmospheric pressure), temperature and humidity plays a small factor.
 
It will vary some. There is a good read in the Rifles, Barrels, and Ballistics section. @Blancoalex has some great advice as well. Just plugging in some random data on Hornady's site and ONLY changing altitude from 1,000' to 7,000', gives POI change of .4 moa @500 yds and 2.5 moa@1,000 yds

 
I don't know your bullet or velocity, but I can provide an example 'local BC' change for standard conditions at 3,200' -vs- 6,300'.
To begin, I'll guess a 28cal .700 G1BC under ICAO conditions (59degF, 29.92InHg station).

At standard conditions for 3,200' ASL, your local G1BC = .770.
Standard conditions here are 48degF, 26.62 InHg.

At standard conditions for 6,300' ASL, your local G1BC = .845.
Standard conditions here are 37degF, 23.71 InHg.

If your hunting conditions matched standard conditions for altitude, and your beginning BC matched my guess, you could simply adjust BC number.
To get it dead nuts would take local/up to the moment atmos measure and calcs.
 
We live and shoot at 2800 elevation. We hunt at 8000 elevation. I haven't kept a log sheet through the years like Im doing now. But I do know that every trip, my buddies shoot high when we test our rifles before we hunt. I always did too, until I bought the BR2 rangefinder. Whether it does what its suppose to do, and adjusted my hold for higher elevation( I will discuss this more in a second). Or I was lucky could be argued I guess. But while my buddies shot multiple shots adjusting their setups, I fired 2 shots. One at 450ish- direct hit. One at 1300ish- half moa left. Cant remember the exact yardage, shooting at rock faces. And I was shooting my 7mm Allen mag at the time if anyone wondering. So gauging from my experiences, plan on adjusting your scopes once you arrive.

More about rangefinders....

I sold my BR2 and purchased a sig sauer 2400ABS because its more compact. And haven't taken it out west yet. However, shooting and getting my data at home at 60 degrees. Then shooting again at 30 degrees. My sig sauer didn't compensate adequately. I didn't chrono my rifle at 30 degrees, like I did at 60 degrees. But according to my drop data(using very good groups). It appears my gun shot well over 100fps slower. Dropping 1.5 MOA more at 615 yds than when shooting at 60 degrees. My gunsmith, which is a successful competition shooter logs all his shots. He tells me than for every 10 degrees in temperature change, he dials differently for same yardage( about .5 MOA per 10 degrees). It looks to me like my BR2s did that for me. But the Sig sauers aren't. And testing RFs one another day, I ranged 557 yards out my door with Rf temp at 73 degrees. Which was my temperature in my house. Zero angle. Then I hung my RF outside for awhile. Then ranged same target at 38 degrees. and with temps rising that day to almost 50. I ranged again at 40, and again at 50. At 73 degrees it said 8.58 MOA. At 38 degrees it said 8.65 MOA. So .07 change in 35 degree swing. Not even close to what I've experienced while shooting. Or what my gunsmiths data suggests.

Even though I've been shooting long-range for years, It seems like the more I learn the harder it becomes. I'm definetly keeping a log going forward of every shot I fire. Temperature, humidity, what my RF tells me to dial, shot angle, and actual bullet impact. The more I shoot, the harder it seems to be to get a first round 1/2-3/4 MOA direct hit from one day to the next.

Any suggestions on why my sig sauers didn't compensate adequately? Will this RF account for pressure from 2800 feet to 8000 feet like Im assuming the BR2s did?

I'm aware I didn't really answer your question. But figured maybe someone could shed some light on why my RFs aren't adjusting properly. And maybe open the door to you purchasing a RF that elimates the issue you are questioning.
 
I guess I should add that my 200yd zero hadn't changed. And Im shooting Reloader 50. And 195 bergers in a 7MM RUM. 60 degree chrono readings were 2930 fps.
 
Why would your zero not change when going from 2800' to 8000'?
You said you & buddies shoot high when testing rifles before the hunt. Makes sense.
So then you need to reset scope zero or tell the ballistic LRF what your actual zero has shifted to. Otherwise it's calcs are wrong.
 
Yes...Always had to rezero once we got there. But last time...using BR2..I never had too.. Thats in colorado.
Now..in wv..at 2800 elevation and a new sig sauer rangfinder...60 degree day vs 30 degree day.. 1.5 moa lower at 30degrees than i was at 60 degrees. Im wondering if my reloader 50 is too temp.sensative or if my rangefinder isnt programmed correctly, or just doesnt work as advertised. My gun shoots very well. My drop data is accurate.
 
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