Zero change from 1000' to 6000' ????

bowhuntrrl · Sep 25, 2005

I just finalized my zero on friday for my upcoming pronghorn hunt.My Burris w/Ballistic Plex reticle is dead on at 200 yards. I then verified the 300 yard line and was -1", which was as stated by Burris.So far so good. Then I got to thinking about the first time I took my .338 Mag on an elk hunt and found it shooting high when I got there due to the altitude. Since ballistic programs don't cover this problem, I was wondering if anyone had a ballpark guess on how much I should lower my 100 yard zero. I'm thinking 1" will help , but probably still not be enough. I can see that by changing the altitudes in the ballistic software that the trajectories will change, but the differences are not great enough to make a big difference. I would really appreciate hearing about anyone's experiences concerning this.Just in case someone has a "super-duper" ballistic program on steroids that can calculate this, load info is:.277" 140 AccuBond BC of .496, velocity of 3125,altitude of sight in 950',temp at sight in was 70 degrees F. Altitude of hunt is 6000' and temp of 60 degrees. Thanks.

longwinters · Sep 25, 2005

Just so I would not have to wonder if I got it right, I would re-sight in when I got out there. Then no surprises.

Long

Ol` Joe · Sep 25, 2005

Personally I wouldn`t worry about it too much. Check your sight in when you arrive at your hunting area and adjust IF it`s found to be needed. My RCBS program shows ~ .6" change at 300 yds with a 100yd zero and a change from 1000 to 6000 ft elev @70 F.

Anonymous · Sep 26, 2005

John Barsness had a good article on ballistics programs and book data in the latest Handloader magazine. I'd suggest taking a looking at that, and following longwinters advice of re-sighting in at your hunt location.

Boonie · Sep 26, 2005

Dropping your 100 yd zero .5" will raise your 300 yd point of impact by 1.06" at the 1000 Ft elevation
Dropping your 100 yd zero .35" will raise your 300 yd point of impact by 1.07 at the 6000 Ft elavation
Hope this is helpful and is the answer to your question as I understood it. I have a similar problem going from 800 ft elavation to 6500 ft elavation Elk hunting witrh a 338 RUM in Colorado