Forums
New posts
Search forums
What's new
Articles
Latest reviews
Author list
Classifieds
Log in
Register
What's new
Search
Search
Search titles and first posts only
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Forums
Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
Help with a scope? I think it is really a MOA question
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Message
<blockquote data-quote="Bart B" data-source="post: 127413" data-attributes="member: 5302"><p>For what it's worth, across several internally adjusted scopes of the same make and model, one can easily find a few percent differences in how far a given change on the adjustments move bullet impact. That's 'cause lenses used in optics have tolerances in their focal length. Two percent is common and a one percent tolerance is rare and costly. When one adds up all the tolerances, it's going to explain why the physical image size at the adjustment plane varies across several scopes. Which means a given adjustment change will result in a smaller bullet impact change for a larger image (from longer focal lengths) at the adjustment plane than a smaller image (from shorter focal lengths).</p><p></p><p>The mechanics across a given make and model have close to zero tolerance. A given thread count and length of the erector tube between pivot and adjustment point are fixed. So these parts will give the same amount of movement per click/mark; lost motion and slop excluded.</p><p></p><p>The only scopes that have exactly the same movement per click are the externally adjustable ones having mounts spaced the same distance apart. Lens focal length doesn't come into play with these as its simple mechanical movement and uniform threads per inch of the adjustments that make 'em this way.</p><p></p><p>The result of lens focal length and pivot arm length of the erector tube combined with exactly how far the mechanics move per click/mark determines the movement. It ain't always exactly 1- or 1.0472-inch (whatever you believe is correct) at 100 yards per MOA of adjustment change. Again, only the externally adjusted scopes moving exactly .002-inch on a 7.2-inch mount spacing that moved impact exactly 1 inch at 100 yards per MOA of change. Makers of internally adjusted scopes may quote some movement per adjustment, but manufacturing tolerances rarely make it so.</p><p> </p><p>It pays to determine your scope's impact change per click/mark of adjustment. 'Tain't easy, but can be done and will resolve a lot of problems when "exact" stuff is needed.</p></blockquote><p></p>
[QUOTE="Bart B, post: 127413, member: 5302"] For what it's worth, across several internally adjusted scopes of the same make and model, one can easily find a few percent differences in how far a given change on the adjustments move bullet impact. That's 'cause lenses used in optics have tolerances in their focal length. Two percent is common and a one percent tolerance is rare and costly. When one adds up all the tolerances, it's going to explain why the physical image size at the adjustment plane varies across several scopes. Which means a given adjustment change will result in a smaller bullet impact change for a larger image (from longer focal lengths) at the adjustment plane than a smaller image (from shorter focal lengths). The mechanics across a given make and model have close to zero tolerance. A given thread count and length of the erector tube between pivot and adjustment point are fixed. So these parts will give the same amount of movement per click/mark; lost motion and slop excluded. The only scopes that have exactly the same movement per click are the externally adjustable ones having mounts spaced the same distance apart. Lens focal length doesn't come into play with these as its simple mechanical movement and uniform threads per inch of the adjustments that make 'em this way. The result of lens focal length and pivot arm length of the erector tube combined with exactly how far the mechanics move per click/mark determines the movement. It ain't always exactly 1- or 1.0472-inch (whatever you believe is correct) at 100 yards per MOA of adjustment change. Again, only the externally adjusted scopes moving exactly .002-inch on a 7.2-inch mount spacing that moved impact exactly 1 inch at 100 yards per MOA of change. Makers of internally adjusted scopes may quote some movement per adjustment, but manufacturing tolerances rarely make it so. It pays to determine your scope's impact change per click/mark of adjustment. 'Tain't easy, but can be done and will resolve a lot of problems when "exact" stuff is needed. [/QUOTE]
Insert quotes…
Verification
Post reply
Forums
Rifles, Reloading, Optics, Equipment
Long Range Scopes and Other Optics
Help with a scope? I think it is really a MOA question
Top