Altitude changes to POI

[Lhedrick1]

Just wondering if there is a "rule of thumb" or generalization for the POI change with an increased elevation.

For example, if I site in my 257 Roy a 1 1/2" high @ 100 yards @ 700', how much higher will it shoot at 100 yards at say 6000', 8000', or 10000' above sea level?

Also, does cartidge make a huge difference?

 

[HiMtnHntr]

It will have some effect. Just plug your data into a ballistics app to give you an idea. Sight your rifle at 700' to reflect that predicted change, and then shoot in the real conditions when you are there.

 

[BIGJOHNT]

Altitude does make a difference for sure. But there is a lot more to it then just adjusting for altitude. A ballistic Computer program will help you out. For hunting I use a G seven range finder. But there are so many apps for your phones. That link to your range finder and the phone threw bluetooth. Kestrel, Sig and Leica may be a few to look at.

 

[Zeke]

It will make SOME difference at 100 yards but you'd only notice it if your gun shoots in the 5's or better. It's quite difficult to see a real POI shift at such a close range.

Where you WILL see a real difference is when the ranges lengthen and there's less drag on the projectile.

Even out to 300 yards probably won't amount to a hill-of-beans for big game hunting. You'll begin to see some changes as you stretch it out.

If nothing else, get on the computer and play with Hornady's ballistics program and see for yourself....but nothing beats real-world experience.

Zeke

#livelikezac

 

[Zeke]

I did some calculations for you (with the help of a ballistics program, of course).

The difference in POI at 100 yards between 0' elevation and 8000' elevation is ONE TENTH OF AN INCH. Like I said, not enough that you can probably tell.

IF EVERYTHING REMAINS THE SAME the difference between 0'elevation and 8000' elevation at 700 yards is almost exactly 9". That's enough to have a significant impact on POI. (pun intended)

It becomes even more critical to compensate for: elevation, pressure, temperature, humidity, spin drift and wind drifts as the ranges extend but most of us should stick to paper at extremes.

There.

Zeke


#livelikezac

 

[deadibob]

I live and shoot at 5,000'. If I go up or down a few thousand feet it's not enough to make a difference.

 

[Zeke]

Like deadi said, it you're only traveling a little, it will only make a little difference until ranges get longer.

5000' v 8000' at 700 yards is only 2" difference. Not eneough to worry about.

5000' v 8000' at 1000 yards is 10 " difference so it starts to make a difference if you're shooting paper or gongs that far.

Zeke

#livelikezac