Altitude and Ballistics

[derquhart]

I am trying to find a ballistics calculator that will tell me the effects of altitude while using a fixed zero point at a different altitude.

Example; I have a 200 yard zero at 500' - if this stays constant, what is my new zero point and ballistics if I am at 8000'?

There are plenty of calculators to adjust for altitude but they are all assuming a new zero point at the new altitude. Appreciate any help!

 

[Zeke]

LAST EDITED ON Jun-09-15 AT 12:08PM (MST)[p]I see what you're saying. The calculations for altitude assume you'll re-sight for 200 yard zero at the higher elevation.

If you know how high you are at 100 yards (currently, at your 500' elevation), then take that same number for 100 yards and apply it to your calculator for 8000' and that should be dang close to exact.

That way you should know what effect it will have on your current 200 yard zero and trajectory beyond that.

Zeke

 

[sageadvice]

LAST EDITED ON Jun-09-15 AT 03:24PM (MST)[p]i mainly concern myself with where exactly my first shot thru a cold barrel hits in the country i'm going to be hunting.

Maybe it's just me but i have noticed when hunting over 10K', my bullets seem to drop a bit less on game taken out there over 3-400 yards.

Joey


"It's all about knowing what your firearms practical limitations are and combining that with your own personal limitations!"

 

[derquhart]

>LAST EDITED ON Jun-09-15
>AT 12:08?PM (MST)
>
>I see what you're saying. The
>calculations for altitude assume you'll
>re-sight for 200 yard zero
>at the higher elevation.
>
>If you know how high you
>are at 100 yards (currently,
>at your 500' elevation), then
>take that same number for
>100 yards and apply it
>to your calculator for 8000'
>and that should be dang
>close to exact.
>
>That way you should know what
>effect it will have on
>your current 200 yard zero
>and trajectory beyond that.
>

Good Idea, essentially back in to it if the math is correct. 1.3" high @ 100yrds/500' so to back in to 1.3" high while at 8000' my new zero would be 205 yards. Out to 500 yards would be 2" less drop at the higher elevation, so not huge but could make the difference.

 

[mtmuley]

Sierra Infinity will do what you are looking for. mtmuley

 

[BruceMc]

Pejsa is a simple ballistics program that is free. Just google Pejsa Ballistics and you should find a site to download from. It has variables for altitude, barometric pressure, and temperatrue.

 

[Zeke]

Finding a ballistic program isn't an issue but it's keeping a current zero and applying it at altitude.

I think the OP is on the right path now.

There's more to exterior ballistics than just altitude, of course. Are density changes through temperature and humidity create scenarios that affect POI.

Zeke

 

[BPKHunter]

I think you may be overthinking it. This assumes you are hunting and not trying to win a shootinc competition.

I use Shooter and can't be happier. I don't shoot at critters at 1000+ yds yet, but am have shot a lot at targets to 1000 and critters to 750. As long as my data for my zero is input correctly, and then my adjustments for Elev and temp are correct, my offset for my yardage and angle tells me where my bullet drop is consistently.

If you zero at 200 or 100 yds, goes up or down less than an inch after changing 5000 or even 8000' it has not practical differrence in the game you kill. More importantly, it has not practicaal difference in the aiming point if you encounter a critter at that range. You will never, with a modern cartridge and moderate BC bulet, need to adjust your hold at your zero, because of a change in elevation.

I only pull out the smartphone and start inputting data at 500 plus yards myself as I usually have drop lines in my scope that will easily have me within 2" of drop so I don't need to worry. This is from 3000' to 10,000'. The exception is when the critter and situation leaves me plenty of time, then I usually set up and thend dial it in, just because I can.

 

[Gator]

See more misses because of a wind drift then from Altitude change.
A Good wind meter will help you alot, BUT remember that it will only tell you the wind where you are standing NOT at the target.
You will still have to dope the wind out there.

"I have found if you go the extra mile it's Never crowded".
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