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#6085455 - 12/15/15 12:55 PM Scope / Bore Misalignment
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
I have a buddy who recently purchased a new rifle and scope that he had bore-sighted at the gunshop. Before firing the first shot we pulled the bolt and looked down the bore to verify alignment with the scope crosshairs and it looked spot on with the target bullseye. We then fired the first shot, the bullet impact was 5’ to the right of the targets bullseye. We ended up having to use windage adjustable scope bases to get the rifle on target because there was not enough windage adjustment in the scope itself. Elevation was spot on after bore-sighting the scope. At this point we assumed that the scope base holes in the receiver were not in alignment with the bore of the rifle and improperly drilled at the factory. After fine tuning the scope adjustments and shooting a 2” group with factory ammo we pulled the bolt and noticed that the view through the rifle bore and scope were not in alignment, with at least 5’ of variance (with the crosshairs on the bullseye, the bore points 5' to the left). This has us perplexed because even if the holes in the receiver were not aligned properly with the bore the scope reticle should be pointed at the same point as the bore of the rifle when the rifle is shooting a 2” group around the target bullseye. Is that a correct assumption? If so, what could be causing this perceived issue? Holes in the target appear round/normal, range was 100 yards.

Brandon

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#6085491 - 12/15/15 01:11 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
ChadTRG42 Offline
THF Trophy Hunter

Registered: 09/16/09
Posts: 9398
Loc: Lewisville, TX
If the rifle is zero'd at 100, the reticle cross hairs should also be at 100 yards. I bore sight many, many rifles the exact way you describe, and I often get it within a few inches of zero. I make sure the scope is dialed down to the lowest power setting when bore sighting in this manner.
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#6085499 - 12/15/15 01:13 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
glb1955 Offline
Bird Dog

Registered: 07/21/11
Posts: 305
Loc: Brazos County Texas
Was the windage set to neutral? You should have more R/L windage available if you put those crosshairs at neutral and then bore sight the best you can using the rear base (which I believe you wrote that you are using). Had that happen to me before.

g

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#6085525 - 12/15/15 01:20 PM Re: Scope / Bore Misalignment [Re: ChadTRG42]
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
Originally Posted By: ChadTRG42
If the rifle is zero'd at 100, the reticle cross hairs should also be at 100 yards. I bore sight many, many rifles the exact way you describe, and I often get it within a few inches of zero. I make sure the scope is dialed down to the lowest power setting when bore sighting in this manner.


Same here, we usually have the rifle on paper when we bore-sight by looking down the bore of the rifle. That is why we are perplexed, the scope is zeroed at 100 yards but the bore appears to be pointing 5' to the left of the target bullseye. Maybe we are missing something simple but it seems odd to say the least.

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#6085587 - 12/15/15 01:47 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
RiverRider Online   content
THF Trophy Hunter

Registered: 11/11/07
Posts: 6204
Loc: Wise Co.
What kind of rifle? Kinda sounds like the bedding may be really, really bad. But then again, a 2" group doesn't really seem to say so. Weird.
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God I am hating caliber threads more and more

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#6085592 - 12/15/15 01:49 PM Re: Scope / Bore Misalignment [Re: glb1955]
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
Originally Posted By: glb1955
Was the windage set to neutral? You should have more R/L windage available if you put those crosshairs at neutral and then bore sight the best you can using the rear base (which I believe you wrote that you are using). Had that happen to me before.

g


We used the rear base to make large adjustments then fine tuned with the internal adjustment. The perceived issue is that when the rifle scope is zeroed at 100 yards it is not in alignment with the bore of the rifle. I realize that sounds crazy but it explains why we couldn't get the rifle bore sighted (at the range looking down the bore or with the bore sighting tool at the gunshop). We had to use a large sheet of plywood just to figure out where the bullet was impacting at 50 yards and make adjustments from there. I have never had to do that before.

Could an improperly cut crown cause such an issue?

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#6085593 - 12/15/15 01:49 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
FiremanJG Offline
THF Celebrity

Registered: 12/16/08
Posts: 17893
Loc: Wolfe City, TX
Rifle and scope are in fact zeroed. Obviously since the scope is allowing the rifle to hit where the scope is "looking", but on re-boresighting you're way off to the left. My bet is the scope has a major malfunction.

What scope is it?
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#6085604 - 12/15/15 01:54 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
RiverRider Online   content
THF Trophy Hunter

Registered: 11/11/07
Posts: 6204
Loc: Wise Co.
I think a crown problem would disperse shots all over the place, but maybe not.

I had an AR that had a bad upper receiver and the barrel ended up pointed off to one side. Sighted in at 25 it would be off to the side about a foot at 100 yards. Sighted in at 100, it was off to the other side at 25 or 50. Bushmaster took care of it, no problem really, just a PITA.
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Originally Posted By: Cleric
God I am hating caliber threads more and more

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#6085605 - 12/15/15 01:56 PM Re: Scope / Bore Misalignment [Re: FiremanJG]
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
Originally Posted By: FiremanJG
Rifle and scope are in fact zeroed. Obviously since the scope is allowing the rifle to hit where the scope is "looking", but on re-boresighting you're way off to the left. My bet is the scope has a major malfunction.

What scope is it?


Correct, the bullet is impacting the target within 2" of where the scope is "looking". Pull the bolt and look down the bore and you would swear the rifle should be shooting 5' to the left. The scope is a Vortex Diamondback.

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#6085638 - 12/15/15 02:05 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
I did loan him a Leupold scope and we witnessed the same thing so we don't think it is a scope issue. We have been debating this issue for weeks now and can't come up with a good explanation.

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#6085669 - 12/15/15 02:19 PM Re: Scope / Bore Misalignment [Re: RiverRider]
Brandon S. Offline
Woodsman

Registered: 05/19/12
Posts: 138
Loc: Sachse, TX
Originally Posted By: RiverRider
What kind of rifle? Kinda sounds like the bedding may be really, really bad. But then again, a 2" group doesn't really seem to say so. Weird.


It is a Savage Model 11, 308 caliber.

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#6085676 - 12/15/15 02:25 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
RiverRider Online   content
THF Trophy Hunter

Registered: 11/11/07
Posts: 6204
Loc: Wise Co.
You could always try another barrel since they can be changed readily.
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Originally Posted By: Cleric
God I am hating caliber threads more and more

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#6085752 - 12/15/15 02:56 PM Re: Scope / Bore Misalignment [Re: RiverRider]
QuitShootinYoungBucks Online   content
THF Trophy Hunter

Registered: 11/01/12
Posts: 6452
Loc: Lubbock, TX
Originally Posted By: RiverRider
You could always try another barrel since they can be changed readily.


This idea has promise.
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#6086121 - 12/15/15 06:44 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
BigPig Online   content
THF Trophy Hunter

Registered: 08/27/09
Posts: 9484
Loc: Forney, Tx
Does the bases look like they are square with the receiver or pointed off to the side?
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#6086130 - 12/15/15 06:47 PM Re: Scope / Bore Misalignment [Re: Brandon S.]
Tff caribou Offline
Veteran Tracker

Registered: 08/27/12
Posts: 2996
Loc: Watauga, TX
Slightly bent barrel? If you stretch out past 100 what happens? Does impact move to the other side?
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