Moved scope ahead, how much zero change?

223submoa

223submoa

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Hi everyone,

I had my rifle zeroed pretty much perfectly, but needed to adjust the eye relief a little bit. I moved the scope ahead one slot on my one piece base. This will change the POI correct? Does anyone know approximately how much at 100 yards? Will I even still be on paper? Thanks for any input!
 
My guess is that you will be on paper, but the POI will change.
Dont forget, if there is any play at all in the slots, push the rings as far forward as possible
to take up the slack.
 
Theoretically, if everything was perfectly straight and true it would make no difference at all. In the real world where nothing is perfect you could be just about anywhere. With typical ring spacing a change of .001" in the X or Y axis will equal 1" at 100 yards. That last part won't help you, I just threw it in to show that a difference that you can't see can change things a lot.

Slide it ahead and see what you get. Chances are it won't change very much.
 
I just went to a field near my house and did a quick re zero. The windage and elevation were both off by about 6 minutes. Still on paper, but WAY off. Thanks guys!
 
What is the MOA of your base?
If it is ZERO there should be no difference.
Before I go any further please explain how a 25MOA picatinny base works? If my thinking is right it could not be 25MOA for its full length, because you get the MOAs by grinding the base at an angle. If this is proper thinking, please correct me if I am wrong, if you are at the last rear notch in your rail, and go forward 1 notch, and you can re-tighten every thing exactly the same as it was, your POI should be higher.
Thanks to all trying to make me understand.
 
You'll have to sight in again.
"a field near my house" HAHAHAHA. There'd be a thousand cops running around here. snicker.
 
sunray said:
You'll have to sight in again.
"a field near my house" HAHAHAHA. There'd be a thousand cops running around here. snicker.
Click to expand...

I live in a farming community with many coyotes. The sound of gunfire is nothing out of the ordinary here. Haha.
 
RIFLEF said:
What is the MOA of your base?
If it is ZERO there should be no difference.
Before I go any further please explain how a 25MOA picatinny base works? If my thinking is right it could not be 25MOA for its full length, because you get the MOAs by grinding the base at an angle. If this is proper thinking, please correct me if I am wrong, if you are at the last rear notch in your rail, and go forward 1 notch, and you can re-tighten every thing exactly the same as it was, your POI should be higher.
Thanks to all trying to make me understand.
Click to expand...

A 25MOA mount tips the scope down at an angle equal to 25MOA. This causes the rifle to shoot 25MOA high, therefore you must dial the elevation knob 25MOA down to get back to zero. You now have effectively created an extra 25MOA of elevation "room" to adjust for longer ranges. I hope his help you understand the principle of using these mounts.
 
RifleDude said:
A 25MOA mount tips the scope down at an angle equal to 25MOA. This causes the rifle to shoot 25MOA high, therefore you must dial the elevation knob 25MOA down to get back to zero. You now have effectively created an extra 25MOA of elevation "room" to adjust for longer ranges. I hope his help you understand the principle of using these mounts.
Click to expand...

I'll add that moving the scope forward also brings the centerline of the scope closer to the centerline of the action, thus changing your point of impact more then you would really think..........on a flat base it is all in how close your rings go back into the same relative position to everything else as you are not moving the entire scope up or down hill
 
RifleDude said:
A 25MOA mount tips the scope down at an angle equal to 25MOA. This causes the rifle to shoot 25MOA high, therefore you must dial the elevation knob 25MOA down to get back to zero. You now have effectively created an extra 25MOA of elevation "room" to adjust for longer ranges. I hope his help you understand the principle of using these mounts.
Click to expand...
In my example I talk about a Picatinny rail, you talk about a mount, this is not just semantics.
In my mind when you move your scope bases forward and say for argument's sake that from your rear scope base being at the last notch in the rail, but your front base can be moved forward by 4 notches, always with the same distance between the bases, you no longer benefit from a 25MOA rail, because the slope is no longer as pronounced in the forward position. Let's leave eye relief out of the equation.
 
RIFLEF said:
In my example I talk about a Picatinny rail, you talk about a mount, this is not just semantics.
In my mind when you move your scope bases forward and say for argument's sake that from your rear scope base being at the last notch in the rail, but your front base can be moved forward by 4 notches, always with the same distance between the bases, you no longer benefit from a 25MOA rail, because the slope is no longer as pronounced in the forward position. Let's leave eye relief out of the equation.
Click to expand...

You have no idea how a 25 moa base works............the entire base it sloped and the OP moved both rings at the same time ahead one notch, which will infact move the scope down closer to the bore and effect point of impact.

If you only move one ring at a time and or leave the eye relief set the same then this will not be the case.......
 
6moa windage and elevation is a lot to me, it shows that something either wasn't in proper alignment to start with, or isn't now, although factory actions (if its one) certainly often have the holes off alignment, 1 notch on the rail shouldn't have thrown it off that bad.

I switch scope between rifles, rings stay on scope, but I've moved it a few notches front, back, so long as I dial it to the rifles zero its always bang on and windage definitely never changes.

So what I'm saying is, triple check your setup.
 
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