zeroing issues


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bugeyed_99
November 2, 2010, 09:26 AM
I have a millett lrs 6-24x installed on a mossberg 4x4 .338 win mag. When i zero at 100yards and move out to the 200 yard mark it hits 6 inches high instead of about 3" low. Any ideas as to why this could happen.

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627PCFan
November 2, 2010, 11:19 AM
Do you accidently have an elevated base/rings? 10 or 20 MOA set on the gun?

chas08
November 2, 2010, 12:09 PM
How high is your scope above the barrel? This affects trajectory a great deal. Also is the scope level with the barrel?

TonyAngel
November 2, 2010, 12:25 PM
That sounds about right. I don't remember the exact specs on the .338 win mag, but if you zero at 100 yards, when the bullet passes 100 yards it's still on it's way up. With a 100 yard zero, you'll likely be hitting high to 250 yards or so, I believe. With a caliber like that, you'd be better off with a 200 yard zero.

You need to find a ballistics calculator. I think hornady has one at www.hornady.com/ballistics

Al Thompson
November 2, 2010, 12:43 PM
Something's off with the scope/bore angle. I'm not familiar with the Mossberg, but it does sound like you have the bases reversed or something that's effecting the angle. Ballistics would not be in play as most designs have the bullet first crossing the line of sight at about 25 yards. If you then zeroed at 100y, the 200 yard impact should be (as you correctly stated) low.

TonyAngel
November 2, 2010, 12:46 PM
OK, I just ran it through a ballistics calculator and Al's right. Something is amiss.

JDMorris
November 2, 2010, 12:49 PM
remove scope and bases, put bases on with the one you now have forward, remount scope, shoot again. if it works. good. if not, new bases will help

bugeyed_99
November 2, 2010, 01:05 PM
It takes the same bases as the rem 700, the back base is slightly larger then the front one. Ive got low rings coming , right now it has factory high rings.

Al Thompson
November 2, 2010, 01:53 PM
back base is slightly larger then the front one :confused:

That would be exactly correct. Rings should not matter.

Can you get a scope that you know is good and shoot a group? That way you can eliminate the weakest link first. :(

bugeyed_99
November 2, 2010, 03:44 PM
I dont see how it would be the scope, i can shoot sub MOA at 100 yrds. Its when i push out the shot goes high

627PCFan
November 2, 2010, 05:45 PM
See post #2. If your bases arent the same, your probably getting some elevation. You may zeroed at 100, but that bullet is still going up to hit high @ 200....... What is your ring and base combo? Where did you get it?

bugeyed_99
November 2, 2010, 06:20 PM
The rings came with the millett scope not sure of brand, the base is a weaver style front and rear.im going to check the level tonight,

rcmodel
November 2, 2010, 06:28 PM
Unless the scope is 12" inches above the receiver, there is no way an elevated base, 20 degree base, or mismatched rings could cause a 100 yard zero to shoot 6" inches high at 200.

The trajectory of the .338 is fairly flat, but it's certainly not still climbing at 200 yards if it is truly zeroed at 100 yards.

As you stated in your OP, if it is zeroed at 100 yards, it should be dropping about 3" at 200 with a normal 2.5" scope height above the bore.

Any of the above mount problems would simply not cause it to shoot higher at 200 then it is at 100.
The Laws of physics prevent that from happening!

rc

bugeyed_99
November 2, 2010, 09:45 PM
RC
Any ideas on a cure for this issue? Something is not working with the law of physics here. Im putting low rings on it approx 1 " in height. Going to the range sat so hopefully i can figure something out.

wyocarp
November 2, 2010, 10:15 PM
Have a another person shoot your rifle and confirm that it is a rifle problem.

chas08
November 2, 2010, 10:46 PM
Does it have an aftermarket muzzle break installed?

bugeyed_99
November 2, 2010, 10:49 PM
As stated before i shoot MOA groups at 100 yards. So i dont see a reason to confirm if its the gun and scope or something else ( shooter )

bugeyed_99
November 3, 2010, 12:10 AM
Factory installed brake

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