Home Forums Hunting & Shooting Hunting Rifles Zero'd at sea level. How high at altitude?

Subject has the question.
Shooting .270 win. Barnes 130 TTSX. 2900 fps.
100 yard zero at sea level. Hunting at 8,000.

How high will it be?

Thanks in advance!

Wsmnut

I zeroed in Utah at about 5500'. Shot about 1-1/4" high there. I shot in Pennsylvania at about 900 feet. The group was 1/2" below the bullseye. So that should give ya an idea.

Shoot a few shots when you get there. Only way you'll know!

Wsmnut: I used to sight in every year at the SPAA range on the tide flats just south of Seattle - elevation 12 feet.
Then I would head on over to the high country of Wyoming with my various Rifles to Hunt Mule Deer and Antelope at up to 8,000' elevation.
I did this for 3 decades.
Indeed there is a distinct and consistent change in point of impact at the higher elevations as compared to sea level!
I heard the atmosphere is only 85% as dense at 6,000' as it is at sea level - which makes it easy to understand the differences.
I often Hunted with various 270 Winchester Rifles but always used Nosler bullets in them.
I would just stop and verify the bullets impact point when I got to my destination.
Doesn't make much difference in point of impact at 100 yards but out at 400 yards it can cause a miss.
My W.A.G. in your case would be the bullet striking 1 1/2" to 2" higher at 8,000' than at sea level (at 100 yards).
There are numerous on-line ballistic sites where you can enter your bullet info (including various altitudes!) and you can print out your info at both elevations.
I use the JBM site:

www.jbmballistics.com/

I hope they are still "in business" (free site!) as I now live at 5,400' and sight in at 6,000' and do not need to compensate anymore or re-adjust my P.O.I.
Best of luck on your Hunt.
Hold into the wind
VarmintGuy

If it's hot when you sight in at sea level and much cooler when you get to your hunting altitude, the difference may not be as much as you'd think.

+1. Your Density Altitude may not be much different. I've seen zero point of impact shift from 500' ASL to 7,000' ASL in most cases.

Yep, we zero at 300' and when hunting at 10k you don't have to change the scope setting. Trajectory is flatter, but not much. Along the lines of 2" flatter at 400. Its so close that I don't really pay it much attention after many kills from up close to 450.

Ditto.

Same here. Often sighted in near sea level and hunted at 11k and never had an issue.

Really the only effect is a drop in drag on the bullet as elevation increases due to the reduction in atmospheric density. This has the same impact as improving the BC of your bullet. Run through some of the exterior ballistic programs out there and you will see that the above mentioned replies are dead on. Little change until you get out there quite a ways.