Scopes: Minute of Angle??

[Sling Shot]

I am planning on purchasing a Leupold 6.5x20x40 for my rifle in .308 caliber. The Leupold scope has 48 minutes of adjustment. According to what I have read, that would be 24 minutes of angle up and 24 minutes of angle down if the scope is optically centered and the windage is centered. My question is if I were shooting a .308 caliber rifle, how would I figure the maximum distance in yardage of the scope before it would run out of elevation adjustment? Thanks, Sling Shot

[Rex Feral]

You need to create a trajectory chart that will plot the bullet drop for your particular bullet weight and velocity (use a computer program, it's easiest) and figure out the range when your bullet drop exceeds your scopes adjustment range. 1 MOA being 1"@100yd, 2"@200yd, 3"@300yd, etc, etc. By my trajectory charts for my 168gr@2660fps load, your scope would run out of adjustment at about 725yd.

However, it is rare to have your scope optically centered AND zeroed for your particular range. How far is far enough? You will have to resort to tapered bases or shims if you want to really reach out there.
My PSS w/Leupold 3.5-10X40LRM3 and 20MOA tapered Badger Base can adjust for better than 1200yd, but the .308 is really running out of steam beyond 800yd.

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Cry "Havoc!" and let slip the dogs of war.

[This message has been edited by Rex Feral (edited March 04, 2000).]

[Michael]

Slingshot, Here's the average come-up chart for 308 Win using 165/168 grain loads. 150 grain loads will be close, and this should give you an idea of the range limitations of the scope you're using.
100=0
200=+9
300=+12
400=+14
500=+16
600=+18
700=+21
800=+23
900=+26
1000=+29
All references are in 1/4 minute clicks.
Your scope will probably have only 22 accurate minutes of adjustment, since as you get closer to either end stop the adjustments
tend not to be true measurement.
Hope this helps.

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Either learn to hit what you aim at, or take track lessons.

[Rex Feral]

Just to alleviate any confusion I should point out that Michaels come-ups chart does not mean 29 1/4 MOA clicks to get from 100 to 1000yd but a total of 168 clicks. 200yd clicks plus 300yd clicks plus 400yd clicks, etc, etc, up to the range you are shooting at.

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Cry "Havoc!" and let slip the dogs of war.

[Sling Shot]

Thanks Rex and Michael for the information. I am going to be shooting the Federal match 168 grain bullet and the information provided will help a lot. OK, let me see if I have this trajectory thing right. If I am zeroed at 100 yards, and I wanted to shoot a target at 600 yards, I would have to come up 18 minutes or 72 1/4 minute clicks. Is this correct? I will have to check on a trajectory program in the near future, but the information that you all provided has helped me understand trajectory. Thanks

[This message has been edited by Sling Shot (edited March 04, 2000).]

[Rex Feral]

At the published velocity of the Federal 168gr Gold Medal load (2600fps)with a 100 yd zero, at 600 yd your drop would be about 107.5" so 72 1/4 min clicks or 18 MOA is correct.

[This message has been edited by Rex Feral (edited March 04, 2000).]

[This message has been edited by Rex Feral (edited March 04, 2000).]

[Virginian1]

Go to www.premierreticles.com for all you ever wanted to know about Leupold scopes, MOA
and long range precision shooting. You will not be disappointed.

Virginian