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AR front post

Started by Brown, February 27, 2012, 06:18:09 PM

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Brown

Ok I need to replace my front post for my AR and need a little assistance. When shooting the 5 square the current front post is HUGE. think looking at a billboard VS that little square.

What I am after is a 4 moa front post. Do any of you have the calculations done or have a front post that is exactly the same size as the square?

My current is app .100" wide, Bushy AR15 with 20" barrel. Going to order a smaller post but would like to order one and not shot gunn it.
I have noticed you get things done and I respect that-SPQR

Francis Marion

Take the measurement from your eyeball to the front post, in inches, and call that "R". 

The width of a 4 MOA front post, in inches, is
R in inches times theta in radians.   

Theta, per your spec, is 4 MOA, which is (4/60)° * pi radians/180° = 0.001164 radians,

So (R inches times 0.001164 radians) is the desired width in inches of your proposed 4 MOA front post.


techres

Your front post is gonna appear about 8MOA.  A match sight can be gotten at half that size.  That should solve your problem.

If you want to be exact, then do the math in the above post.
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Aromatic

#3
Your rear aperture diameter is not a factor in the calculation.

http://appleseedinfo.org/smf/index.php?topic=26402.0

I use a 0.062" from WOA  it is not 4MOA... :)

http://www.whiteoakarmament.com/xcart/product.php?productid=17707&cat=256&page=4

Brown

I just KNEW someone was gonna make me do math :'(

thanks for the help all!
I have noticed you get things done and I respect that-SPQR

brianheeter

I just got my AR together.  My front post is about 8 MOA and I wanted something nice and pointy.  A little bit of poking around and I found this:  http://www.midwayusa.com/product/427154/kns-front-sight-post-assortment-ar-15-matte-package-of-7  Ooops!   Looks like I got the last one.  You can find it elsewhere.  I think I measured my 8 MOA post at around .07" wide on a 20" barrel.  This set gives you that and some thinner ones to choose from.  I haven't put them on yet (stupid job, it cramps my style!) but I'm looking forward to trying the square vs. the round vs. the "V" vs. the inverted "V."

C ya,

brian
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grunt soldier

Quote from: Aromatic on February 27, 2012, 07:00:13 PM
Your rear aperture diameter is not a factor in the calculation.

http://appleseedinfo.org/smf/index.php?topic=26402.0

I use a 0.062" from WOA  it is not 4MOA... :)

http://www.whiteoakarmament.com/xcart/product.php?productid=17707&cat=256&page=4

I run this same front sight post. it's just right imo.
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