Rifle Scopes Verifying Scope Leveling Q???

[Grump]

Yeah, I read everything, but...

IF the group at the longer-distance zero elevation is off to the right by 3/4-inch at 100 yards, compared to the 100-yd zero group,

what direction do you rotate the scope for the final adjustment?

My "mental gymnastics" said to rotate right, clockwise, by enough to bring the vertical crosshair over the slightly displaced shot group.

Right or wrong???

 

[deadly0311]

Re: Verifying Scope Leveling Q???

rotate it away from the group. If its throwing shots to the right, its canted to the right, bring it back to the left

 

[Grump]

Re: Verifying Scope Leveling Q???

Great. Now I get to re-zero.

Now that I think about it, it's NOT like correcting the crosshairs to where the rounds hit when zeroing...

 

[M40_A1]

Re: Verifying Scope Leveling Q???

Grump,
I was avoiding having to do the mental gymnastics. It is getting harder for me to figure 3-dimensional problems out than it was when I was younger. Go figure!

Every visual aid I am coming up with now is saying that if the target line is vertical and you are holding the vertical crosshair on the vertical line, then it would group on that vertical line throughout its travel regardless of scope cant in relation to the rifle. However, I know that's not the case because the method has worked for me in the past. It's downright frustrating.

I <span style="font-style: italic">believe</span> you would need to rotate the scope clockwise in the scenario you describe, but I'm not 100% sure, and I'm embarrassed to say so. The best I can do for you would be to say try clockwise, and if that doesn't work, go the other way.

You WILL have to rezero your scope, but DO NOT rezero your scope until you have the scope rotated to where it needs to be. Like I said before, the groups don't have to be on the line, as long as the groups are all parallel to (the same distance from) the vertical target line. THEN you will know the scope is set right, and you can rezero with confidence.

Anyone who can help figure this out and explain it, please do.

BTW, what preliminary scope leveling procedure did you use?

 

[Grump]

Re: Verifying Scope Leveling Q???

10X:

I used the feeler gages to level to the base, bot it's a hammer-in SAI 2-point mount.

dialing "up" to the 500 Z moves reticle down on tgt, so impacting right means reticle went left compared to the bore, correct?

I used to be good with visual stuph...

 

[Johnsusername]

Re: Verifying Scope Leveling Q???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">Yeah, I read everything, but...

IF the group at the longer-distance zero elevation is off to the right by 3/4-inch at 100 yards, compared to the 100-yd zero group,

what direction do you rotate the scope for the final adjustment?

My "mental gymnastics" said to rotate right, clockwise, by enough to bring the vertical crosshair over the slightly displaced shot group.

Right or wrong??? </div></div>

Is the elevation off?
It may be spin drift. What range is the longer range at?

John

 

[Grump]

Re: Verifying Scope Leveling Q???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: John F</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">Yeah, I read everything, but...

IF the group at the longer-distance zero elevation is off to the right by 3/4-inch at 100 yards, compared to the 100-yd zero group,

what direction do you rotate the scope for the final adjustment?

My "mental gymnastics" said to rotate right, clockwise, by enough to bring the vertical crosshair over the slightly displaced shot group.

Right or wrong??? </div></div>

Is the elevation off?
It may be spin drift. What range is the longer range at?

John


</div></div>
Sorry to be a bit harsh this morning, but RTFP.
RTFT.

Read the Fabulous Post.

Read the Fabulous Thread.

100 yards. No spin drift between the two groups. Verifying. Elevation zero was established at 600 yards, but the wind blows around here. We verify scope leveling not at distance, but by going back to 100 and dialing up on a plumb target and watching for horizontal drift.

If the line of the vertical crosshair does not intersect the center of the bore, tilting the scope UP to correct for the crosshairs going down will point the barrel off to one side or the other.

 

[M40_A1]

Re: Verifying Scope Leveling Q???

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Grump</div><div class="ubbcode-body">
If the line of the vertical crosshair does not intersect the center of the bore, tilting the scope UP to correct for the crosshairs going down will point the barrel off to one side or the other. </div></div>

This would be true if the rifle is straight but the scope canted. With the scope vertical and the rifle canted, I'm not so sure anymore (if all shot at the same range).
PM sent, Grump.

 

[Grump]

Re: Verifying Scope Leveling Q???

Here's the report:

If you have the crosshairs on the aiming point, you twist the scope OPPOSITE of the way the plus-elevation group struck.

Think of it as the higher group is the "true" windage zero, and you need to rotate the scope to bring the crosshairs under that group.

Nothing like live fire to make things real.

 

[M40_A1]

Re: Verifying Scope Leveling Q???

Thanks, grump.

 

[Snakum]

Re: Verifying Scope Leveling Q???

I got the best advice ever about checking scope leveling here when mine started heading left past 500 yards. I used a small bubble level to set up the gun in the vise and the scope in the rings, and was still off just enough for it to show at longer ranges. It was essentially this:

http://www.arcanamavens.com/LBSFiles/Shooting/Downloads/ScopeChecking/

 

[Lindy]

Re: Verifying Scope Leveling Q???

Well, thanks.

Allow me to point out, though, that small angles of scope cant are not very problematic.

With a typical .308, it takes a 5 degree cant angle to throw a shot off 1 MOA at 100 yards - which is the same magnitude of deviation caused by a 1 mile per hour crosswind.

Five degrees is a <span style="font-style: italic">very</span> noticeable angle. Get the reticle so it looks level when the rifle is level, and you'll be fine.

A level attached to the rifle is very useful when shooting off a canted surface like the side of a mountain.