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Zeroing a milrad scope w/BDC - quick help Login/Join 
Web Clavin Extraordinaire
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posted
Helping a guy zero a scope tomorrow. It's a Burris 1-5x24 with a MRAD reticle.

Never dealt with a MRAD scope, only MOA. I understand that 1 mil is 1 cm at 100 yards, roughly.

My primary question is regarding the zero distance. Normally I would zero an AR at 50. After skimming the manual for the Burris scope yesterday, I didn't see that it said what distance to zero at so the BDC works as intended. (Primary Arms, for instance, tells you to zero at X, Y or Z yardage with A, B or C loads for the BDC to function.)

What I presume is that the reticle on this Burris requires a 100 yard zero, since the center dot under the horseshoe is the 100 yard aim point, according to the diagram.

Is it that simple? Again, 100 yard zero is not my first choice, but if that is what the reticle requires, I'd rather give this guy the simplest answer possible.

And what is the easiest process for zeroing? Should I print out a 1 cm grid just to make life easy, or deal with the ~1/3rd" adjustments on a one inch grid target I already have?


----------------------------

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Educating the youth of America, one declension at a time.
 
Posts: 19697 | Location: SE PA | Registered: January 12, 2001Reply With QuoteReport This Post
Gracie Allen is my
personal savior!
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FWIW:

http://www.snipercountry.com/mrad-vs-moa

My understanding is that zeroing is at 100 meters, which works out to 109.3 yards (about 109 yards and one foot). Per the article above, that should give you 1/10th of a milliradian = 1 cm at that distance.

Since 1 cm is a hair under .4 inches (.39XXX, given 2.5401 cm to the inch), I'd be tempted to just go ahead and work with a 1 inch grid unless you have a 1cm grid handy.
 
Posts: 26675 | Location: Deep in the heart of the brush country, and closing on that #&*%!?! roadrunner. Really. | Registered: February 05, 2008Reply With QuoteReport This Post
Member
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Like the PA ones you zero at 100 yds.
https://www.burrisoptics.com/b...actical-cq-and-gen-3

Like so.


The BDC is in yds, scope adjustments are in MIL.
 
Posts: 1089 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
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This should be that reticle.


Windage dash lines are 5cm
 
Posts: 1089 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
Freethinker
Picture of sigfreund
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There’s no reason not to zero an MRAD reticle at 100 yards if that’s what the BDC part of it requires. It won’t be quite as convenient as having an MOA reticle and target with 1/4 inch grids, because as stated, 0.1 milliradian equals 0.36 inch at that distance if we’re trying to use the measured distance of the point of impact for adjustments. But because both the reticle and adjustments are in MRADs, no calibration markings on the target are necessary: just use the reticle as the ruler.

For example, if you see by the markings on the reticle that your group is 0.5 mil low and 0.3 mil right, just adjust the scope up five clicks and left three.
That said, based on the diagram of the reticle that I believe you’ll be using, it may require some interpolation to use because the vertical line is not calibrated in mils. I would find the diagram that shows the milliradian values of all the reticle elements, print it off, and have it available when zeroing. That’s not as convenient as using a reticle that’s fully calibrated in milliradians, but might be usable enough to get you close.

And that scope evidently has a second focal plane reticle, so remember that in order for the markings, including the BDC, to be accurate, it will be necessary to use it at one magnification—probably the maximum.

Added: And FWIW, it’s 0.1 mil at 100 yards that equals 0.36 inch; at 100 meters 0.1 mil = 1 cm (exactly). One milliradian equals 3.6 inches at 100 yards.




7/93
 
Posts: 45712 | Location: 10,150 Feet Above Sea Level in Colorado | Registered: April 04, 2002Reply With QuoteReport This Post
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It looks like the 400 yd and up dash marks are for ranging.
Torso wide is the range estimation.
 
Posts: 1089 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
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quote:
And that scope evidently has a second focal plane reticle, so remember that in order for the markings, including the BDC, to be accurate, it will be necessary to use it at one magnification—probably the maximum.

Yes max power for no math calculations.

Though knowing the holdovers for when it's on 1x is handy.

25 yd holdover on 1 is the same for 200 on 5
 
Posts: 1089 | Location: Portland Oregon | Registered: October 01, 2011Reply With QuoteReport This Post
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