I'm curious if any of you have seen or done any kind of studies about how altitude can impact your trajectory. I know many outside factors, such as temp and air density, will have an impact on a bullets flight, but am just not sure to what extent. I'd really like to hear some numbers such as x load dropped y less inches at 500 yards when going from sea level to 10,000'.
Altitude and Trajectory
- Thread starter ammoman16
- Start date
sageadvice
Long Time Member
- Messages
- 11,849
Not scientific by any means but i killed a nice 28" 170 class 4x4 at over 10,000 ft elevation a couple seasons ago and i hit 4-5" higher than i expected.
I was locked in prone position, had ranged the buck at 360 yds. Was shooting a custom barreled Rem 700 in 280AI, 140 gr combined tech bullets built with 60 1/2 grs of imr 4350 that had crono'd at 3190 fps. 2 1/2" high at 100yds, dead on-to 1" low at 300, 8-9" low at 400 as shot from my make due, out of town range. Being the buck was uphill from my position but not excessivly so, i held for 300yds, middle to high shoulder, instead of allowing for 4-5" of drop if the 360yds were completely horizontal.
I was locked in tight, solid steady, and when the gun barked, i just knew that he was dust and he did drop dead on the spot. Surprised me very much and still a mystery to this day when i recovered the animal. i had hit 4-5" directly above expected, where the cross hairs had been when she barked. Altitude? It could maybe had something to do with it, good question.
joey
I was locked in prone position, had ranged the buck at 360 yds. Was shooting a custom barreled Rem 700 in 280AI, 140 gr combined tech bullets built with 60 1/2 grs of imr 4350 that had crono'd at 3190 fps. 2 1/2" high at 100yds, dead on-to 1" low at 300, 8-9" low at 400 as shot from my make due, out of town range. Being the buck was uphill from my position but not excessivly so, i held for 300yds, middle to high shoulder, instead of allowing for 4-5" of drop if the 360yds were completely horizontal.
I was locked in tight, solid steady, and when the gun barked, i just knew that he was dust and he did drop dead on the spot. Surprised me very much and still a mystery to this day when i recovered the animal. i had hit 4-5" directly above expected, where the cross hairs had been when she barked. Altitude? It could maybe had something to do with it, good question.
joey
I just ran some values through my ballistics program (Sierra Infinity) and all else being equal there is a 5" difference in bullet drop from 0'---10,000'.
This was a .308 caliber 180 gr. Nosler ballistic tip @ 3000 fps
5" can be enough to make a poor shot on deer sized game and being in mountainous terrain angle shots create a much larger factor.
This was a .308 caliber 180 gr. Nosler ballistic tip @ 3000 fps
5" can be enough to make a poor shot on deer sized game and being in mountainous terrain angle shots create a much larger factor.
>I just ran some values through
>my ballistics program (Sierra Infinity)
>and all else being equal
>there is a 5" difference
>in bullet drop from 0'---10,000'.
>
>
>This was a .308 caliber 180
>gr. Nosler ballistic tip @
>3000 fps
>
>5" can be enough to make
>a poor shot on deer
>sized game and being in
>mountainous terrain angle shots create
>a much larger factor.
>
But that being said I don't know of very many people that sight their guns in at sea level and then hunt at 10,000'. Also at what range was it off by 5". If it's 600 yds or more, the guys shooting that far are probably shooting about 6" or larger groups at that range considering that they can keep it MOA...
>my ballistics program (Sierra Infinity)
>and all else being equal
>there is a 5" difference
>in bullet drop from 0'---10,000'.
>
>
>This was a .308 caliber 180
>gr. Nosler ballistic tip @
>3000 fps
>
>5" can be enough to make
>a poor shot on deer
>sized game and being in
>mountainous terrain angle shots create
>a much larger factor.
>
But that being said I don't know of very many people that sight their guns in at sea level and then hunt at 10,000'. Also at what range was it off by 5". If it's 600 yds or more, the guys shooting that far are probably shooting about 6" or larger groups at that range considering that they can keep it MOA...
It is nice to live here. The local range is about 5,000 and I use the bench rest, practice and sight horizontally at that facility. However, I also practice and use the chrono at 7,500 more than once each year. It's not scientific, but my experience says the bullet drops a little less the higher the elevation. I doubt it's enough to cause a miss on deer/elk.....unless sea level to 10,000 and an extreme distance.
R
redrabbit
Guest
One can imagine the number of hunters from Texas and Georgia, states with low elvations, heading to Colorado to hunt elk every year and being ignorant of the effects of elevation, temp, barometric pressure.
