80 vs 100 yard trajectory.

[MountainApache]

Hello all!
So, I'm living in western NC and with all of this virus stuff I'm kind of staying low. I'm not able to travel to a long range spot to shoot a rifle but here on my family's land I have access to our usual 80 yard range that we usually use to sight in our deer rifles for mountain hunting (shots under 200 yards). My only problem is that I'm trying to break in my new 300 wby and would like to use the 300 yard zero that they have on their sight. Obviously, before I go hunting in the fall I'll double check my zero on a longer range but for now I am wondering. How far off would my rifle be if I sighted in in at 80 yards ( shooting 3 inches high) instead of dead on having it sighted in at 100 yards shooting 3 inches high? Thanks in advance!

 

[Gwine]

Just changed my 7 RM to an 80yd zero on Streloc and it did not affect the 300 yd trajectory from my 100yd zero.

 

[MountainApache]

Awesome. That's great to know. I didn't know that f that 20 yards would make a big difference on the 300 yard zero.

 

[cohunt]

Did the same on my 7rm 162's and I get .1 moa difference or 1/2" between 80 and 100 yards.

 

[MountainApache]

Did the same on my 7rm 162's and I get .1 moa difference or 1/2" between 80 and 100 yards.

Just out of curiosity, is it 1/2 inch higher or lower when zeroed at 80?

 

[Lefty7mmstw]

why not just zero at 200 or more? I don't worry about short range zero unless I'm shooting a pistol...

 

[UplandFreak]

why not just zero at 200 or more? I don't worry about short range zero unless I'm shooting a pistol...

He only has access to an 80 yd range. He is trying to zero his gun at 300 yards using an 80 yard target...

 

[MountainApache]

why not just zero at 200 or more? I don't worry about short range zero unless I'm shooting a pistol...

I'm trying to achieve the 300 yard zero, but I only have access to an 80 yard range at the moment. Here in NC the governor has a lot still shut down so my ability to travel to a longer range is hindered.

 

[AZShooter]

With little information on what bullet, velocity, elevation etc, I chose Ashville and used 2500 ft elevation. 180 nosler ballistic tip @ 3150 fps (per Nosler manual) 70 degrees 65% humidity

There is quite a difference between 3" high at 80 vs 100 yds




3" high at 80 yds

75​	2.8​
100​	3.8​
125​	4.6​
150​	5.1​
175​	5.3​
200​	5.3​
225​	5.0​
250​	4.5​
275​	3.6​
300​	2.5​
325​	1.0​
350​	-0.7​
375​	-2.8​
400​	-5.2​

3" high at 100 yds

75​	2.2​
100​	3.0​
125​	3.5​
150​	3.8​
175​	3.9​
200​	3.7​
225​	3.2​
250​	2.4​
275​	1.4​
300​	-0.0​
325​	-1.7​
350​	-3.6​
375​	-5.9​
400​	-8.5​

I suggest you manipulate JBM's program to see exactly what your rifle should do and later shoot it at longer distances.

JBM - Calculations - Trajectory

www.jbmballistics.com

 

[Lefty7mmstw]

I'm trying to achieve the 300 yard zero, but I only have access to an 80 yard range at the moment. Here in NC the governor has a lot still shut down so my ability to travel to a longer range is hindered.

gotcha... get her 2" or so high and she'll be close enough... we never lost our 200 yard range here... I prefer to set up at 400+ but that's a hell of a drive or a membership fee... I just do some deer scouting while I take the drive...