I have a BCM 14.5" Midlength Upper with F marked FSB and LMT Rear sight also..

what is the MOA (per se) of the front sight post at 100 yards???

I have 16 3/4" from the rear 'peep', to the TDC of the F marked FSB 'post'..

I know its bigger than my old 3MOA RDS...

Anyone have a way to figure this out mathmatically... (or just have a number for me)

nevermind.. 12.665 MOA is what someone posted back in 2009 on here..

if someone has a SIMPLE math way to do this.. chime in..

This question comes up from time to time. It is a simple equation.

The Front Sight of a M-4 Carbine is ~19" from your eye, if you shoot NTCH, roughly.

0.035/19 = 0.001842105

100 yards is 3,600 inches.

Then,

X/3,600 = 0.001842105

(3,600) * X/3,600 = 0.001842105 * (3,600)

(3,600) * X/3,600 = 0.001842105 * (3,600)

X = 0.001842105* (3,600)

X = 6.63158

Since this was an Isosceles Triangle, you need to double this number.

Then means that a 0.070" Front Sight Post, 19" from your eye, covers ~13.26" at 100 yards, or 12.665 MOA

There is another equation to get you where you need to go.

Site width is W (in this case 0.070")
Distance from eye to sight is R (in this case 19")
A circle has 360 degrees, and there are 60 minutes per degree, so a circle has 21,600 minutes

To find the MOA of your sight:
21,600 * (W / (2 * 3.14159 * R))

The circumference of a circle with your eye at the center and the sight at the edge:
(2 * 3.14159 * 19) = 6.28318 * 19 = 119.38042

How much of it the sight covers:
(W/119.38042) = 0.070/119.38042 = 0.0005863608

Multiply that times the minutes in a circle:
0.0005863608 * 21,600 = 12.665 minutes.

In this case (19"), your front sight would cover about 12.7 MOA.

so if I can get my 100 yard.. 50 shot groups down to say 8" while shooting offhand or kneeling I am on the 'right' track.. seeing how I have a 12.XX" front sight MOA..

on a front BAG I am great from a bench.. but standing/kneeling I'm still at like 12" groups..

heres a 14"w x 22"h target I shot today.. with like 100 rounds of Federal AE 223 55gr FMJ..

volley #1 is in the circles..

volley #2 is not circled.. I got a decent group of about 8" on the right hand (heart area) side if you look closely..



any suggestions other than slow down and stop jerking the trigger??

Not sure what the front sight post but lets use 4moa for the example....i always thought that if it is 4moa at 100yard it is also 4moa at 5yard or 1000 yards because the distance is calculated into the formula to calculate the moa.  Did i misunderstand this?

The only suggestion that ppl can give you is to make sure you are taking natural breaths and firing at the natural pause in between breaths and work on trigger control (squeeze it straight back and pin the trigger back on each shot if you are shooting for accuracy).  The vertical spread is due to breathing (assuming you are holding steady on your POA) and the horizontal discrepancy is due to trigger control.  Work on it....get out there and go through thousands of rounds.  That is the only advice to give.

No, you understood it correctly.

4MOA @ 100yds is ~ 4.2" , but ~42" at 1000yds.