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Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
Getting a reticle level is nearly impossible .
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<blockquote data-quote="bruce_ventura" data-source="post: 684442" data-attributes="member: 34084"><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">This thread has wandered around a bit and come back to a few folks suggesting that accurate reticle alignment is as simple as aligning the reticle or the bottom of the scope precisely parallel to the base. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">Well, yes and no. These simple methods work fine for short range shots in which elevation adjustments are generally less than about 10-15 MOA (about 500-700 yds for most high power centerfire calibers). At short range the canting error is so small that most folks won't notice it. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">These simple alignment methods would work for long range shots <u>IF</u> all of the following were true:</span></span></span></p><p> </p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The barrel is straight.</span></span></span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The barrel is centered inthe receiver.</span></span></span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The barrel and receiver axes are parallel.</span></span></span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The base(s) and receiver axes are parallel.</span></span></span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="color: black"><span style="font-family: 'Calibri'"><span style="font-family: 'Calibri'">The ring and base(s) axes are parallel.</span></span></span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The rings are centered on the base(s).</span></span></span></span></span></p><p> <span style="color: black"><span style="font-family: 'Times New Roman'"></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"></span></span><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">Or, if the person doing the reticle alignment gets really lucky and all these factors cancel each other out. It happens, but not very often. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">The problem is that a rifle in which all of the above criteria are true is very rare (in my experience). In fact, it is rare to find a rifle in which more than half of these requirements are met. </span></span></span></p><p><span style="color: black"><span style="font-family: 'Times New Roman'"> </span></span></p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">Unless the rifle is uber precisely machined and assembled from start to finish, these simple reticle alignment methods will lead to a significant systematic canting error for long range shots, even if an anti-canting level is used. That's because the simple alignment criteria of having the scope parallel to the base is not sufficient. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">To remove these systematic canting errors the projection of the elevation turret axis must pass through the center of the bore (at the muzzle, where it matters). In most mid- to high-end scopes the reticle is parallel/perpendicular to the turret axes. Therefore it is usually sufficient to get the projection of the reticle to pass through the center of the bore. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">JE Custom's first post describes a live fire method for achieving this reticle alignment condition. The live fire method works, but is time-consuming and expensive. It is possible to align the reticle optically to the same degree of accuracy. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">Winmag's first post describes a process in which he aligns the reticle using plum lines and levels. Then he creates a large optical bench out of his kitchen and back yard, and uses it to confirm that the reticle is properly aligned to the bore. This is essentially an optical version of the live fire method. </span></span></span></p><p> </p><p><span style="font-family: 'Calibri'"><span style="color: black"><span style="font-family: 'Calibri'">I use a different optical process that is easier for me. My optical method requires the scope tube to be horizontally parallel to the bore (i.e., horizontally "boresighted"). There are other benefits of boresighting the scope tube, so I always do it when installing a scope. I use a device like the EXD Engineering alignment instrument to plumb the reference line intersecting the scope tube and rifle bore axes. Then I level the reticle and I'm done. </span></span></span></p></blockquote><p></p>
[QUOTE="bruce_ventura, post: 684442, member: 34084"] [FONT=Calibri][COLOR=black][FONT=Calibri]This thread has wandered around a bit and come back to a few folks suggesting that accurate reticle alignment is as simple as aligning the reticle or the bottom of the scope precisely parallel to the base. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]Well, yes and no. These simple methods work fine for short range shots in which elevation adjustments are generally less than about 10-15 MOA (about 500-700 yds for most high power centerfire calibers). At short range the canting error is so small that most folks won’t notice it. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]These simple alignment methods would work for long range shots [U]IF[/U] all of the following were true:[/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [COLOR=black][FONT=Times New Roman][FONT=Calibri][COLOR=black][FONT=Calibri]The barrel is straight.[/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [FONT=Calibri][COLOR=black][FONT=Calibri]The barrel is centered inthe receiver.[/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [FONT=Calibri][COLOR=black][FONT=Calibri]The barrel and receiver axes are parallel.[/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [FONT=Calibri][COLOR=black][FONT=Calibri]The base(s) and receiver axes are parallel.[/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Calibri][FONT=Calibri]The ring and base(s) axes are parallel.[/FONT][/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]The rings are centered on the base(s).[/FONT][/COLOR][/FONT] [FONT=Calibri][COLOR=black][FONT=Calibri][/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [/FONT][/COLOR][FONT=Calibri][COLOR=black][FONT=Calibri]Or, if the person doing the reticle alignment gets really lucky and all these factors cancel each other out. It happens, but not very often. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]The problem is that a rifle in which all of the above criteria are true is very rare (in my experience). In fact, it is rare to find a rifle in which more than half of these requirements are met. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]Unless the rifle is uber precisely machined and assembled from start to finish, these simple reticle alignment methods will lead to a significant systematic canting error for long range shots, even if an anti-canting level is used. That’s because the simple alignment criteria of having the scope parallel to the base is not sufficient. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]To remove these systematic canting errors the projection of the elevation turret axis must pass through the center of the bore (at the muzzle, where it matters). In most mid- to high-end scopes the reticle is parallel/perpendicular to the turret axes. Therefore it is usually sufficient to get the projection of the reticle to pass through the center of the bore. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]JE Custom’s first post describes a live fire method for achieving this reticle alignment condition. The live fire method works, but is time-consuming and expensive. It is possible to align the reticle optically to the same degree of accuracy. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]Winmag’s first post describes a process in which he aligns the reticle using plum lines and levels. Then he creates a large optical bench out of his kitchen and back yard, and uses it to confirm that the reticle is properly aligned to the bore. This is essentially an optical version of the live fire method. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [COLOR=black][FONT=Times New Roman] [/FONT][/COLOR] [FONT=Calibri][COLOR=black][FONT=Calibri]I use a different optical process that is easier for me. My optical method requires the scope tube to be horizontally parallel to the bore (i.e., horizontally “boresighted”). There are other benefits of boresighting the scope tube, so I always do it when installing a scope. I use a device like the EXD Engineering alignment instrument to plumb the reference line intersecting the scope tube and rifle bore axes. Then I level the reticle and I'm done. [/FONT][/COLOR][COLOR=black][FONT=Times New Roman][/FONT][/COLOR][/FONT] [/QUOTE]
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Getting a reticle level is nearly impossible .
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