Two zeros

S

sfwusc

New member
I have my 30-06 (165g corelokt) at 100 yards.

How can I figure out my second zero? I found a web site that estimate 25 yard zero to hit dead on again at 243 yards, but I would think a longer distance original zero would have the second zero closer to the original.

Any thoughts? (Did I make sense?)
 
First, you will need to know how high the scope centerline is above the bore axis. A scope that's 2 inches above the bore will have a different first zero than a scope that is one inch above the bore.
If the scope is even with the bore vertically, your first zero will always be at the muzzle.

I suggest going to an online ballistics calculator such as http://www.jbmballistics.com/cgi-bin/jbmtraj-5.1.cgi and plugging in your velocity, bullet weight and style, zero range, etc, and looking at the trajectory and you will get a good idea of where the first zero will be.
 
I just went to the JBM ballistics calculator and plugged in 160 grains, a BC of .3, and a muzzle velocity of 2800 fps.

With iron sights .75 inches above the bore, a rifle shooting this bullet will have a first zero at about 15 yards with the second zero at 200.

Using a scope that's two inches above the bore, the first zero happens at 40 yards with the second zero at 200 yards.

Sight makes a difference and if you don't know what it is, there is no way we can give you a first zero for whatever yardage you want the rifle to be zeroed at.
 
Shoot it at varying distances until you find out exactly where your second zero is. Then you can calculate a very exact muzzle velocity and run your calcs even further if ya want.
 
My software, the Oehler Ballistic Explorer, uses a default scope sight height of 1½" and gives a near zero of 61 yards for the 165 grain Core-Lokt cataloged as #R3006B.
 
Google "Point Blank" & get a copy (you download & its inexpensive.)Just plug in the numbers & run your trajectories.
 
If you have a Droid phone, download Strelok...
It's free...and accurate. Don't leave home without it!
 
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