High-quality, low-cost precision rifle rig

Slight correction - the Army battlesights at 300m, the idea being the line of sight intersects flight path of the M193 round at 25 and 250 meters. For the M855 round, the Army uses same procedure as the Marines with the A2 - zero with sight turned back one click from 300m at a 25m zero target.

zeroA2.jpg
 
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Slight correction - the Army battlesights at 300m, the idea being the line of sight intersects flight path of the M193 round at 25 and 250 meters. For the M855 round, the Army uses same procedure as the Marines with the A2 - zero with sight turned back one click from 300m at a 25m zero target.

zeroA2.jpg

I promise you that the Marines zero at 36 yards with 8/3-1 on the rear sight. Not 25 yards.
 
I remember those old iron sights lol... made me glad we went with the new optics :) It makes it so much easier when you don't have to mess with all of the adjustments... until the battery goes lol.
 
I remember those old iron sights lol... made me glad we went with the new optics :) It makes it so much easier when you don't have to mess with all of the adjustments... until the battery goes lol.

Yeah, so glad that such batteries will be easy to come by in the PAW. ;)

Actually, I've been thinking about putting a regular old glass non-electric 2x7 scope on the AR. 2x shouldn't hamper acquisition very much at near ranges, and 7x is more than enough at 500 yards. But my eyes aren't what they used to be, and I'm starting to drop rounds pretty bad at 500.
 
25m = 27 and one third yards and the Army goes one click up on M855 for the 350m setting:

M855_drop_during_25-meter_zeroing_trajectory_M16A2_M4.jpg

The M855 from a full sized M-16 A2 20" barrel at 3100 fps precisely co-witnesses at 36yd and 200 yd. one click back from 300 yards is 200 yards. 8/3-1 is 200 yards.

If you zero at 36yd with sights on 8/3-1 (200 yard sight setting) then your round will impact 0.3" low at 200 yards. Then you click up to 8/3 and zero at 300 yards proper.

A 25 yard zero with M855 co-witnesses just under 265 yards.

I promise you I'm not guessing about this.
 
USGI M855 62gr penetrator green tip

Calibre: 5.56mm
Weight: 62gr
Ballistic Coefficient: 0.301 G1
MV: 3100fps
 
I understand that the M4 has a lower muzzle velocity because of the short barrel, but I never touched an M4 in the Marines, nor do I know the proper MV to verify the path of the M855 on a ballistic chart.

Bear in mind that if your ballistic coefficient is off it can dramatically effect your plot.
 
I understand that the M4 has a lower muzzle velocity because of the short barrel, but I never touched an M4 in the Marines, nor do I know the proper MV to verify the path of the M855 on a ballistic chart.

Bear in mind that if your ballistic coefficient is off it can dramatically effect your plot.

MV on the M4 is 2600 fps - each inch of barrel costs about 100 fps.
 
Here is the chart for a 36yd zero with M855 from a full size A2.

Bear in mind that one click back from the 300yd sight setting IS the 200 yard sight setting.

It wouldn't make a lick of sense to zero on the 200 yard sight setting if the trajectory co-witnesses at 300 yards.

n175vl.jpg
 
I note that a 25 yard zero does co-witness with 200yd from the M4, so it makes sense that the M4 zeroes with 8/3-1 at 25 yards.

See the previous chart for evidence that a 36 yard zero co-witnesses with 200yd from the full sized barrel M16
 
Honestly, my advise is just buy something you can afford. And a lot of ammo. And practice with it. A lot. There is a bloody legacy of iron sights killing other humans. Jerry Miculek can damn near squeeze off as many rounds on a single-pull as an automatic. Practice makes perfect. Imperfect practice is wasted time.
Right... but for new users with a precision rifle will be more encouraged to learn about range finding, windage, and drop aspects which is actually a good thing to know.
 
Marines zero at 300 also, the short range zero is just to 'get on paper.' Once you are zeroed at 36yd (M16) or 25yd (M4) you verify your initial zero at 200, and THEN you click back up to 8/3 and perfect your BZO at 300 yards proper.
 
Also good discussion here: http://www.m4carbine.net/showthread.php?t=65679

The other sight, marked 0-2 (the Army calls it the low visibility sight - which makes no sense) will zero at 200m if the rifle has been properly zeroed with the other sight.

The only time we were allowed to use the gigantic site was night firing with gas masks on. :p And that was only if we couldn't use the regular rear sight, and the Marines who had to go to the huge one were made to feel like blind fools for doing it lol.
 
It appears that the primary calculation difference here is sight height. Calculating for the full 2.6" you would indeed co-witness to 300yd, BUT to do that you want to put your rear sight on 8/3 not 8/3-1

M16 at 36 yd:

nzro9l.png


M4 at 25 yd:

o6zfut.png
 
The only time we were allowed to use the gigantic site was night firing with gas masks on. :p And that was only if we couldn't use the regular rear sight, and the Marines who had to go to the huge one were made to feel like blind fools for doing it lol.

With the round going a good 9 inches above line of sight, something needs to be done for intermediate range - if not the "idiot" sight, then adjusting the zero distance is a good idea - but the drop at distance is astounding.
 
It appears that the primary calculation difference here is sight height. Calculating for the full 2.6" you would indeed co-witness to 300yd, BUT to do that you want to put your rear sight on 8/3 not 8/3-1

What does this all mean? I get the general concept of MOA and how you can adjust your scope to varying distances by clicking it, but what you are talking about is some sort of iron sight adjustment? Is this feature only on M16s and not commonly found on AR15s?

Just trying to understand. Thanks!
 
What does this all mean? I get the general concept of MOA and how you can adjust your scope to varying distances by clicking it, but what you are talking about is some sort of iron sight adjustment? Is this feature only on M16s and not commonly found on AR15s?

Just trying to understand. Thanks!

OK bear with me because I've just had to deal with a burgeoning civil war in the NC Liberty movement and I'm three sheets to the Crown Royal black right now, but I still think I can clarify this.

MOST AR-15's have A2 sights.

p_062111102_1.jpg

The knob on the side controls windage, or the left to right strike of the round. The knob below controls elevation, or the up-down strike of the round. In the image I posted you see the number "10" which means 1000 yards - mind you this is an aftermarket sight so the number "10" does not exist on most AR-15 rear sights.

His is how it normally works:

opplanet-leapers-mnt-95rs05-utg-a2-rear-sight-mount-v2.jpg


OK, now look at the next image:

rearsight3.jpg


Do you see the "8/3" on the knob? One click counter clockwise (as looking from above) is 8/3-1

The 8/3 setting is 800 or 300 yards. 300 near bottom, or 800 near top. Assuming a 360 degree rotation of the knob.

Near the top, 8/3 is the 800 yard setting. near the bottom, 8/3 is the 300 yard setting.

Go one click lower than the 300 yard setting and you are at "8/3-1" which is the 200 yard setting.

Fo TWO clicks lower than the 300 yard setting and you are at "8/3-2" which is the 100 yard setting. In fact, 8/3-2.5 is generally "bottomed out."

The same sights are normally on the M-16 AND the AR-15

Thing is, if you get "MOA" you are already way, way beyond many hard core rifle marksmen in knowledge, because MOA is THE KEY.

If you 'get' MOA everything else follows from that.

This is what I am most grateful to Appleseed for is expounding MOA. We didn't get MOA in the Marines. We got the unsupported positions, we got the "point of aim - point of impact" that most riflemen done get, we got a lot of stuff in the Marines but we didn't get MOA. IMHO MOA is the KEY to understanding rapid zero and sight adjustments. Once you "get" MOA everything else falls in line.

The M-16 and AR-15's with A2 sights are juuuust about 1/2 MOA per click of WINDAGE (side knob) and elevation (bottom knob) should be EXACTLY 1/2 MOA.

I hope that answers the question. If not let me know. Like I said I am 3 sheets to the wind after having to put down a civil war, so I barely know what I am doing right now lmao!
 
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