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Rifles, Reloading, Optics, Equipment
Gunsmithing
HELP: Out of Windage - Scope Base Screw Hole Alignment Check?
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<blockquote data-quote="bruce_ventura" data-source="post: 698796" data-attributes="member: 34084"><p>Farmerbeau,</p><p></p><p>With such short time left, you may not be able to use the proper tools to sort this out exactly. Here's an approach that will help you identify the problem. This method is a bit crude, but is accurate enough to diagnoae a problem of this magnitude. </p><p></p><p>First, find the optical center of the scope. That is done by placing a mirror against the objective rim. I've used my wife's small make-up mirror. You will see two reticles - one is the reflected image. If it's too dark to seethe reflected image, shine a light onto the mirror next to the objective. Rotate the turrets until the two reticle images over lap. If the problem is your scope, you won't be able to do this. I'll bet you a box of ammo your scope is fine. </p><p></p><p>The base holes could be off, but more likely the problem is with the barrel. I'm guessing either the barrel is mounted crooked in the receiver, or the bore is bent, or both. You can check for a crooked barrel by placing a 24-36" metal ruler against the right side of the receiver. Measure the gap between the ruler and the barrel 18" from the receiver. Then repeat for the left side. I'm guessing that the difference between these measurements is at least 0.15". </p><p></p><p>If not, then the problem is either the base mounting holes or the bore is bent. Install the base and back out the mounting screws at least two full turns. If the holes are misaligned the base shouldn't fit properly when you press down on it with your fingers - it will rock like a table with one short leg. </p><p></p><p>If the base fits snug, install the base and tighten the base screws. Now repeat the test above using the metal ruler, only this time place the ruler against the left and right side of the base. If the barrel was centered in the first test, but not in this test, the problem is with the base holes. </p><p></p><p>If everything checks out fine so far, install the base, rings and the optically centered scope. Pull out the bolt and sight something through the bore at least 20 yds away. I would print or draw a 1" dia circle with a cross centered on it. Tape it to a wall or other suitable target stand. Precisely center this target in the bore. If the problem is a bent bore, the scope will be aiming a few inches to the aide of the cross. </p><p></p><p>The real question is how to fix a problem with your rifle in time for the hunt. I would buy a set of Burris Signature rings. The 30 mm rings come with offset inserts. You can orient them to correct for the problem with the rifle. If the misalignment problem is not too severe, Signature rings should get you zeroed. Bed the base if it doesn't fit properly. Then use a torque wrench to tighten all the screws.</p></blockquote><p></p>
[QUOTE="bruce_ventura, post: 698796, member: 34084"] Farmerbeau, With such short time left, you may not be able to use the proper tools to sort this out exactly. Here's an approach that will help you identify the problem. This method is a bit crude, but is accurate enough to diagnoae a problem of this magnitude. First, find the optical center of the scope. That is done by placing a mirror against the objective rim. I've used my wife's small make-up mirror. You will see two reticles - one is the reflected image. If it's too dark to seethe reflected image, shine a light onto the mirror next to the objective. Rotate the turrets until the two reticle images over lap. If the problem is your scope, you won't be able to do this. I'll bet you a box of ammo your scope is fine. The base holes could be off, but more likely the problem is with the barrel. I'm guessing either the barrel is mounted crooked in the receiver, or the bore is bent, or both. You can check for a crooked barrel by placing a 24-36" metal ruler against the right side of the receiver. Measure the gap between the ruler and the barrel 18" from the receiver. Then repeat for the left side. I'm guessing that the difference between these measurements is at least 0.15". If not, then the problem is either the base mounting holes or the bore is bent. Install the base and back out the mounting screws at least two full turns. If the holes are misaligned the base shouldn't fit properly when you press down on it with your fingers - it will rock like a table with one short leg. If the base fits snug, install the base and tighten the base screws. Now repeat the test above using the metal ruler, only this time place the ruler against the left and right side of the base. If the barrel was centered in the first test, but not in this test, the problem is with the base holes. If everything checks out fine so far, install the base, rings and the optically centered scope. Pull out the bolt and sight something through the bore at least 20 yds away. I would print or draw a 1" dia circle with a cross centered on it. Tape it to a wall or other suitable target stand. Precisely center this target in the bore. If the problem is a bent bore, the scope will be aiming a few inches to the aide of the cross. The real question is how to fix a problem with your rifle in time for the hunt. I would buy a set of Burris Signature rings. The 30 mm rings come with offset inserts. You can orient them to correct for the problem with the rifle. If the misalignment problem is not too severe, Signature rings should get you zeroed. Bed the base if it doesn't fit properly. Then use a torque wrench to tighten all the screws. [/QUOTE]
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HELP: Out of Windage - Scope Base Screw Hole Alignment Check?
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