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3/20/2017 5:03:23 PM
Posted: 1/2/2012 7:44:49 PM EDT
[Last Edit: 1/2/2012 7:48:09 PM EDT by semperserveranceSTA]
When using an optic/scope is the measured height over bore from center of objective lense to center of inside diameter of bore? When using isnipe ballistic app this is a question asked so Id like to be as precise as possible.


Psalms 91
Link Posted: 1/2/2012 8:55:35 PM EDT
Use a straight edge or a caliper. A few fractions aren't going to hurt.
Link Posted: 1/2/2012 10:36:09 PM EDT
The measuring is not the problem basically what I'm asking is what is the exact definition of sight-over-bore ... Point A is what and Point B is what
Link Posted: 1/2/2012 10:48:53 PM EDT
The definition is center of objective to center of bore. Use a machinists rule, measure from center of scope tube to the bottom gas hole in the bolt carrier. That will put you in the strike zone.
Link Posted: 1/2/2012 10:50:55 PM EDT
center of objective lense to center of inside diameter of bore

A - center of objective lense
B - center of inside diameter of bore


Link Posted: 1/2/2012 11:45:57 PM EDT
Most optics on the AR flat tops are about 2.5 inches. It's a good rule of thumb, and any ballistic calculator will be very close within a half inch. It's close enough that the difference in the ballistic app is going to need to be field tested anyway at distance to confirm and adjust, since no app is perfect.
Link Posted: 1/3/2012 5:32:13 AM EDT
Holding a ruler isn't the most precise way by a long shot.

The measurement is centerline of bore to centerline of the scope's rings.

If you know your scope mount height and height of the upper's rail over the bore, you can add the two together.

A Vltor MUR's rail is 1.215" over the centerline of the bore.

A Larue SPR 1.5 has a ring height of 1.5".

So, this combination will give you a HOB of.....2.715".
Link Posted: 1/3/2012 6:28:54 AM EDT
I agree with BP's measurements.
Link Posted: 1/3/2012 6:32:38 AM EDT
Thanks y'all I got brain injury from fallujah so I don't know what I'd do with out y'all! I'll be paying my member fee I think
Link Posted: 1/3/2012 6:39:26 AM EDT
Originally Posted By semperserveranceSTA:
Thanks y'all I got brain injury from fallujah so I don't know what I'd do with out y'all! I'll be paying my member fee I think


Thanks for your service. There is a lot of info, and fun on this site. You need a thick skin sometimes though.
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