Can someone check my math?

[mao0720]

So I need to figure out how much to raise my rear sight on my M1a for 600 yds. I do not know the click value of the rear sight because I have a standard rear sight housing with a hooded NM aperture. So I did it the mathematical way. Check my math please.
600yds x36= 21,600in.
Sight radius= 26.5in.
Drop at 600yds 106in.

21600/26.5= 815.09
106/ 815=0.13" THIS SHOULD BE HOW MUCH I NEED TO MOVE MY REAR SIGHT UP FROM MY 100YD ZERO.?. Thanks for the help fellow gun geeks!

 

[MrMajestic]

http://www.brownells.com/.aspx/lid=13093/GunTechdetail/Sight_Correction_Calculator
Brownells says your right!

 

[mao0720]

Didnt know brownells had that. Good to know that my math skills and problem solving are still going strong

 

[firearmdoc1]

Yes .13005 is the correction needed to zero your sights at 600 yds.
Correction Needed x Sight Radius / Range = adjustment required.

 

[jonbearman]

Firearmdoc1,what does the backslash represent,is it divide or what? Dont know the nomeclature.

 

[Uthink Uknow]

÷ = divided by

 

[bheadboy]

a point for those with adjustable rear iron sights. with the front fixed, (say an m1), fire at 100 or 200 and make the same calculations.

them take a set of dial calipers and measure the movement for clicks on the rear. divide the click movement into the number from the formular and you get the clicks to zero,

if you have a crono you can then make adjustment to 300/300/500 etc using drop calculated for the bc/velocity your are using, then divide that or multiply for the needed clicks for the range using the same data.

Bob

 

[mao0720]

Yeah I used dial calipers to measure my rear sight movement to 600 yds. 0.13inches. 17 clicks in that 0.13", makes my elevation adjustment 1moa per click.

 

[ratguner]

A standard M1A should be 1 minute clicks. Rotating the hood allows for 1/2 minute change.

200 to 600 yards is a nominal 14 minute change.

 

[mao0720]

How does rotating the hood allow for 1/2 min change? Is the aperture offset in the hood?

 

[mgx1138]

Yes; the aperture is offset in the hood.

 

[Taildrag15X]

How does rotating the hood allow for 1/2 min change? Is the aperture offset in the hood?

Yes; the aperture is offset in the hood.

Only if it is a 1/2 moa hood, there are alot of standard NM marked hooded sights out there, way more than there are 1/2 moa adjustable ones that have the "NOTCH"..........I think Springfield now includes them with thier NM Service Rifles and I know they come on the Super Match.

For more info check out these Forums..........and if you are a serious M1A guy, join there's a ton of great info there!


http://m14forum.com/gus-fisher/63780-using-nm-hooded-rear-sight-aperture.html


http://m14forum.com/gus-fisher/108594-little-history-nm-sights.html