Sighting-in an M4


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Want2Be
November 20, 2008, 10:01 AM
Anyone have an tips on sighting in a new Bushmaster M4A3? I've read a few different ways online (different distances, different number of shots in teh group), so I just figured I'd get a general idea from the experts

Thanks
-Chris

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HOLY DIVER
November 20, 2008, 11:12 AM
i'm no expert but i dailed mine in at 150yd (because my local range is 150yds)lol i hand load so i had afew diffrent loads to try i forget the exact load that grouped the best but if you want it i know i have it wrote down in my datta book.i shoot a group of 3 clean the rifle make adjustments/repeat process untill i'm happy.as far as factory loaded ammo mil-sup shoots good,black hills,pmc
congrats on your new AR

possum
November 20, 2008, 11:22 AM
i sight my personal weapon in at 50yds, yes that is yds not meters, that should give you only +/- 2 inches from 8-220yds. so that means you can basically aim wherever you want the round to strike from 8-220yds and it will be no more than 2 inches high or low. of course up close you are gonna have to take offset into account but that is true with the ar regardless. i believe that this is the best all around zero, for civilians and police especially, and i would even love to see the army change to that zero too, but as everyone knows the we are stuck in our ways in the army.

the main thing to remember is that what ever zero you descide, keep it and use it, and train with it, figure out where you are gonna hit at the different ranges etc, like getting dope on a precision rifle.

jackdanson
November 20, 2008, 11:26 AM
From what I've read the general rule for an AR is to zero at 25 yards. That's what my manual suggests, and I believe that is what the military zeros at.

woodfiend
November 20, 2008, 11:30 AM
Yeah, cuz if you zero your rifle at 25 yards, it will keep that zero almost out to like 300 yards. I did mine that way and it works.

natescout
November 20, 2008, 11:31 AM
in the marines we zeroed the front sight, shot at 25 yrds and adjusted the front sight in 5 shot groups to get a battle sight zero

1911 guy
November 20, 2008, 12:15 PM
The M16 has one click below the 3/8 sight setting, the M4 has two. Zero at 25 meters two clicks below the 3/8 setting, dial to 3/8 and you'll be good to 300 meters.

Don't take this as gospel, it's been over a decade since I got out, twelve years, to be exact.

KW
November 20, 2008, 12:51 PM
Lots of good info can be found at this site: http://groups.msn.com/themarylandar15shooterssite/zeroingmethods.msnw

I'm a fan of the IBSZ (50 yard method), but there are other ways that may better suit what you plan to do with the rifle.

possum
November 20, 2008, 05:02 PM
From what I've read the general rule for an AR is to zero at 25 yards. That's what my manual suggests, and I believe that is what the military zeros at.
just because the military does it dosen't mean that it is right or the best.

HOLY DIVER
November 20, 2008, 05:50 PM
hey don't over think this, zero the thing in at what ever range you think you'll be using it at the most

taliv
November 20, 2008, 05:57 PM
what possum said the first time... 50 yrds

wcwhitey
November 20, 2008, 06:21 PM
+2 for what Possum said. Set it at 50 yards and forget about it. You can alway adjust a few clicks up or down for bullseye shooting. But you should be able to keep em on a pie plate out to 300 if you do your job. I use the 50 yard method with my A1 carbine (with A2 rear sight) and it works like a charm.

proven
November 20, 2008, 06:33 PM
IBSZ. easy to do and very effective.

http://groups.msn.com/TheMarylandAR15ShootersSite/improvedbattlesightzero.msnw

James T Thomas
November 20, 2008, 06:50 PM
Sir:

Your're getting some erroneous information here; if the Bushmaster is anything like the former military M-16. We are discussing 5.56 x 45 mm ammunition aren't we?

Much of the military did sight them in at 25 meters which is an insignificantly more distance than 25 yards.
That is, the targets were 25 meters distance from the shooter. How ever...

The strike of the bullet at the 25m target was not set by sight adjustment to put the holes on center; the bullseye, at that range!

Because of the bullet following a curved path; not quite a great circle, but what is called a parabola, where the initial curviture is gradual and then at a certain range, the curve increases more and more rapidly. A horizontal stream of water discharged from a garden hose will curve similarly to the ground.

So, the sights were adjusted to cause bullet impact, at 25m, to strike
approximately 2 1/2 inches or 6 cm above {but centered} the bullseye of the target.
With the sight adjusted for that "trajectory," you could aim center mass on the enemy less than 250 m and your bullet would be striking high by that 2 1/2 inches or at the further range of 250 m, strike dead center. Bullseye.

Beyond that range is another matter altogether.

I may be off by a fraction of an inch on that, but it will be close.

Now you must memorize how your target appears at 250 m. Eyes visible?
Face visible? Colors visible? That kind of thing.

jpatterson
November 20, 2008, 07:01 PM
The M16 has one click below the 3/8 sight setting, the M4 has two. Zero at 25 meters two clicks below the 3/8 setting, dial to 3/8 and you'll be good to 300 meters.

Don't take this as gospel, it's been over a decade since I got out, twelve years, to be exact.

That's how I was trained less than 2 years ago. Make sure the front sight post is level with the front sight aperture(?) by screwing it up or down. Do the what 1911 guy says to start with and adjust accordingly.

Good luck!

Pipe Burn
November 20, 2008, 09:52 PM
I am assuming civilian M4's rear sight elevation knob has the same markings as my issue M4 in the Army. An M4 has a 3/6 marking, while an M16/AR15 has a 3/8 on the rear elevation knob. To zero the M4 rifle, you need to have the rear sight set at 3/6, not 3/8 plus one or two. The M4 is different from the M16/AR15. There is a "z" on the M4's rear elevation knob. Many people mistake the "z" on the elevation knob of the rear sight as meaning this is where it needs to be set prior to shooting 25 meter zero and then set back to 3/6 when zeroing is complete. This is incorrect. The "z" has a purpose, but not this purpose. The rear sight dial needs to be set at 3/6 dead on. The zeroing targets the military uses for the M4 print this information on the paper targets because of this common confusion. An M16/AR15 on the other hand, get the 3/8 plus one prior to shooting for 25 meter zero and then is set to 3/8 dead on after zero is complete and confirmed. I want to say the reason for the difference is because the sight radius of the two weapons is different, but I'd be just blowing smoke because I just don't remember.

Fire three rounds at 25 meters at your point of aim. Look at your target and make adjustments. Repeat the process until you get you rounds to hit consistently with your point of aim. Your 25 meter zero will allow you to hit a target out to 300 meters as explained above.

I'm an infantry Platoon Sergeant. I run M4 ranges as well as qualify on them, so my advise is strickly a reflection of how the Army does it. The army is notorious for not doing things the best way, but this way is simple and effective. So take it for what its worth.

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