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Measuring scope height

 
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  #1  
Old 09-25-2009, 08:55 PM
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Location: colorado
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Measuring scope height

Was wondering how everyone here measures the scope height to enter in a ballistic program, I take it that it is from center of bore to center of scope but is that at the front of the scope or middle? I have my scope mounted on a 20 MOA rail and wasnt sure if I should measure it at the front of the obj. or more towards the center of the scope. Any comments would be helpful,

WOOOOO HOOOOOO ELK season is only 3 weeks away
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  #2  
Old 09-26-2009, 09:39 AM
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Re: Measuring scope height

Quote:
Originally Posted by elkstalker300 View Post
Was wondering how everyone here measures the scope height to enter in a ballistic program, I take it that it is from center of bore to center of scope but is that at the front of the scope or middle? I have my scope mounted on a 20 MOA rail and wasnt sure if I should measure it at the front of the obj. or more towards the center of the scope. Any comments would be helpful,

WOOOOO HOOOOOO ELK season is only 3 weeks away
+1 on that, I'm curious as well. Just watched both of Shawns videos and in one section he explained how to use the exbal program, which is where he said his scope height was 2.1" above bore. I always thought it was just 1.5" above so this has me wandering the same thing. If you haven't seen Shawns videos I highly recommend them, very informative and fun to watch.

Nathan
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  #3  
Old 09-26-2009, 10:16 AM
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Join Date: Apr 2007
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Re: Measuring scope height

ES300

Here are some threads a search turned up for reflection:
What defines 'Sight Height'?

measuring scope height using canted bases

What does sight height represent in hollands software program?

Measuring Scope Height??

Sight height measurement

scope height measurement

I think you'll have a hard time coming up with a written reference/definition for this...your best bet if your after that would be to contact your ballistic software producer, and ask what their definition is/how it applies to your specific software.

My opinion-If pressed for an answer, mine would be the "sight height" would be defined as the point/axis where the rifle is rotated when changes in the elevation turret were made on the optic in order to point or aim the rifle at the same target.

Another thought-There might be more worthwhile things in your shooting system to dedicate time/thought too. It was calculated in one of the previous threads linked above that a 20 MOA base is less than .07 difference between the objective height and eyepiece height on a 12" scope....when I apply a .07 variation to sight height, I see no difference in dialed elevation adjustment out to 1500 yds. But like you....I can't stand to be ".07" off on anything

BTW-Those two opinions wasn't formed from any scientific knowledge/analysis, or special prowess on my part, but rather from conversations with some LR "sages" on this board and others in the precision shooting community. My 2 cents...but just barely worth 2 cents

Good luck!
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  #4  
Old 09-26-2009, 02:52 PM
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Location: colorado
Posts: 227
Re: Measuring scope height

Interesting because my program has a considerable differance in just one inch of sight height at 1000 yards, I will check out those links thanks. I am surprised that no one has chimed in with info, it is a common input on calculators so I thought everyone would have a say in this
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  #5  
Old 08-08-2011, 10:22 AM
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Join Date: Jul 2011
Location: Florida
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Re: Measuring scope height

Quote:
Originally Posted by Autorotate View Post
My opinion-If pressed for an answer, mine would be the "sight height" would be defined as the point/axis where the rifle is rotated when changes in the elevation turret were made on the optic in order to point or aim the rifle at the same target.
That's only an issue if you have a 20 MOA Scope base. If you use a standard, level scope base, it won't make any difference whether you take the sight height at the objective lens or the center of the scope. (this is because when you adjust your scope, the reticle moves, not the scope itself, so the height for the center at the turrets and the objective remains the same, assuming level mounting.
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  #6  
Old 08-08-2011, 11:47 AM
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Location: Allen, TX
Posts: 2,608
Re: Measuring scope height

It pays to be as precise as possible. But, you also have to keep things in perspective.

You should be close enough if you measure from the centerline of the bore/bolt/firing pin to the centerline of the scope where the turrets are located. It may make it easier if you meaure top of the bolt to bottom of the scope and add half the scope diameter plus half the bolt diameter.

Any such reasonable measurement should suffice as other shot to shot variables will present a bigger challenge for predicting POI at long range.

e.g. 7RM+180 Berger @ 2600 fps
1.8" scope ht=317.1" drop @ 1k
1.3" scope ht=319.1" drop @ 1k
2" @ 1000 yds < 1/4 MOA (less than 1 click on most scopes)

How much change in MV do you get with a 20 deg change in termperature from the particular powder that you use?

What MOA accuracy can you depend on from your rifle?

JMO
-- richard
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  #7  
Old 08-08-2011, 12:24 PM
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Re: Measuring scope height

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