Iron sight question

ckpj99 · October 10, 2015, 09:06 PM

Ok, somebody check my math please.

The sight radius on my rifle is 31" so the circumference of the theoretical circle that radius would create would be 194.7" (C = 2 x pi x r)

So the distance of 1 degree of that circle would be .54" (194.7 divided by 360 degrees).

So one minute of angle (MOA) of my sight radius would be .009" (.54 divided by 60).

So in order to change my point of impact 1" at 100 yard I need to adjust the height of sight .009", correct?

1stmar · October 10, 2015, 09:13 PM

I believe you are correct however, iirc a simpler formula is sight radius / 3600 or 31/3600=.0086.

ckpj99 · October 11, 2015, 12:08 AM

1stmar - So I reached way back into my middle school algebra training and did some reduction of my formula.

The IIRC formula is good idea because the whole process can be reduced to a single math problem, however, why would they pick 3600?

The actual math calculates to sight radius divided by 3438. If you're going to round 3400 is the best, but even 3500 would be a better estimation.

1stmar · October 11, 2015, 02:31 AM

36 inches in a yard, 100 yards 3600. Iirc= if I recall correctly.

kraigwy · October 11, 2015, 09:25 AM

1stmar is correct.

36 inches in a yard, 100 yards is 3600 inches. The simplest formula is as he said, divide the sight radius by 3600 and that will give you the distance the sight needs to move to move the bullet impact 1 inch at 100 yards.

You can use all the fancy math in the world, and if you use it right, you'll come up with the same answer.

KISS

October 10, 2015, 09:06 PM	#1
ckpj99 Senior Member Join Date: January 24, 2011 Posts: 386	Iron sight question Ok, somebody check my math please. The sight radius on my rifle is 31" so the circumference of the theoretical circle that radius would create would be 194.7" (C = 2 x pi x r) So the distance of 1 degree of that circle would be .54" (194.7 divided by 360 degrees). So one minute of angle (MOA) of my sight radius would be .009" (.54 divided by 60). So in order to change my point of impact 1" at 100 yard I need to adjust the height of sight .009", correct?

October 11, 2015, 09:25 AM	#5
kraigwy Senior Member Join Date: June 16, 2008 Location: Wyoming Posts: 11,061	1stmar is correct. 36 inches in a yard, 100 yards is 3600 inches. The simplest formula is as he said, divide the sight radius by 3600 and that will give you the distance the sight needs to move to move the bullet impact 1 inch at 100 yards. You can use all the fancy math in the world, and if you use it right, you'll come up with the same answer. KISS __________________ Kraig Stuart CPT USAR Ret USAMU Sniper School Distinguished Rifle Badge 1071

October 10, 2015, 09:13 PM	#2
1stmar Senior Member Join Date: March 21, 2012 Location: Connecticut Posts: 2,378	I believe you are correct however, iirc a simpler formula is sight radius / 3600 or 31/3600=.0086.

October 11, 2015, 12:08 AM	#3
ckpj99 Senior Member Join Date: January 24, 2011 Posts: 386	1stmar - So I reached way back into my middle school algebra training and did some reduction of my formula. The IIRC formula is good idea because the whole process can be reduced to a single math problem, however, why would they pick 3600? The actual math calculates to sight radius divided by 3438. If you're going to round 3400 is the best, but even 3500 would be a better estimation.

October 11, 2015, 02:31 AM	#4
1stmar Senior Member Join Date: March 21, 2012 Location: Connecticut Posts: 2,378	36 inches in a yard, 100 yards 3600. Iirc= if I recall correctly.