Variable power scopes and POI changes

timb

timb

New member
Hey guys:
Have a question. I am anxiously awaiting my new DTech to arrive and have bought a 4X12 Leupold to put on it.

If I use a higher power, say 10X, to do my sight in and load work up, am I going to see a noticeable change in my POI, if I use it at 5X to hunt with?

Am kind of new to the variable scope arena, and need some expert advice.

Thanks for your help!

Regards,
Tim
 
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I am no expert but i can say that on my scopes i sight in at high power and develop loads at high power and when i back them down to low power the poi is very much if any different from the sightin on high power. you will definitly hit your game in a hunting situation from my experience.
 
On a well made scope, you will normally see very little or no change in POI with a power change. However, if your requirements require the utmost in precision, even with a cheap scope, sight it in with the power setting you are most likely to be using for hunting purposes .....and leave it there.

The only way you will know for certain if the POI will change with a power change is to shoot the gun at one setting, then do the same at the other setting.
 
Good quality variable scopes under 10X usually will give no problems with POI changes with power ring changes. If they do and it is more than the very slightest of shifts in group impact, the scope has a problem and needs sent back for warranty work. Most shooters will never see this because if there is a tiny shift in POI it is absorbed by the group size and available precision of the rifle, or, shooter technique and error. Over 10X adjustable parralex settings will help with keeping the shot on target. This is a combination of shooter and scope compatability as much as mechanical reliability of the scope.
 
It's been my experience that apparent POI shifts when drastically changing magnification can usually be traced back to incorrect parallax adjustment. The numbers on the AO end (yards, usually) do not often match real world parallax adjustment.

So, if your parallax adjustment is "off" (but not readily noticable) at one setting, changing the magnification also normally causes you to assume a different stock-weld, which compounds the parallax error.

I helped out a guy at the range a couple months ago who was having an apparent shift in POI of almost a full inch at 100 yards when changing from 4X to 12X.. He was ready to toss his hi-$$ varmint scope. I adjusted his parallax setting for the distance he was shooting, and he immediately decided his scope was a pretty good one after all.

Mike
 
First of all, thanks to all that responded. Have a question for Linefinder.

If I do not have an AO, how do I correct parallax? I will be sighting in at 100 yards, and it is my assumption that most big game scopes are parallax free at 100 yards, is that true?

Thanks for your help!
Tim
 
You are correct. Most big game scopes are designed parallax free at 100 or 150 yards. With your scope being non-AO, the situation I described above certainly can't be the problem.

I'm not aware of any method to change parallax adjustments on a non-AO scope.

Before you give up on the scope, pay particular attention to how you set up your shot when changing power. I know on my VXII, the difference in how I have to position my head on the stock is dramatic when I change from 4X to 12X. This may be part of your problem.

Mike
 
I have a steel plate with scope bases mounted on it for checking variable scopes and the adjustments on all scopes. I just mount the scope and clamp the plate to a good concrete bench. I have never seen any variable scope that did not change POI with power change. There is a reason you never see a variable scope on a benchrest rifle. When talking about mid-level scopes a 1 MOA change is fairly common.

Jack
 

Excellent post! This is what I do with my variable scopes. I verify (at the range) the scope's zero at the magnification I'm going to be using for that kind of hunting and then I leave it there. If I DO need more magnification, I'll crank it in but I'm always aware that scopes (even expensive ones) can and do shift impact upon power change ESPECIALLY as they get older!
One thing I used to use and it really did work was a bore sight. I had one of the old Bushnell models. I would zero my rifle and take note of where the bore sight's setting was. I then wrote that down in a notebook. If (for any reason) that scope didn't produce that bore-sight setting, I knew I needed to make an adjustment which was ridiculously easy with the needed setting right in front of me. It worked well and quite frankly, I need to get back to using that method. Only takes a few seconds to check.
 


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