Help w/ zeroing my ar15 at a 25m range, first time.

[topsykretts]

I'm going next week to the philadelphia archery and gun club to zero my ar15 for the first time. Its got a detachable YHM front sight and a magpul MBUS rear sight with windage-only adjustment. I've never zeroed a rifle before, and doing some reading I'm worried it'll shoot too high beyond 25M. I've read everything on the ar15zeroing.com website but I'd be a more confident if someone could explain what I'll be doing as if I'm an 8 year old, or mentally handicapped, or both.

[Legion_Prime]

well first off I think their range is only 50 feet, a good ways shy of 25m, I'm not sure of this though. Second you will want a 25m zeroing target. Then once you get grouped you can zero it in. At 25m each line on the sight should correspond to 1 click on the rear sight and 1 notch on the FSP. Just make sure if you have an A2 rear sight that it is set to 300m + 1 more click. Once you have it zeroed it will be zeroed for 300m with that ammunition. I personally recommend zeroing it with you go to ammo and then just doping it while plinking.
The MBUS rear though I'd say to guesstimate the center, then adjust as needed to get it on the paper and the adjustment notches should roughly correspond to those in an A2 sight IIRC.

[ReconLdr]

If you zero at 25yds you should be able to get hits on torso size targets all the way to 300yds. This being said, your bullet would impact +/- the POA at anything in between.

So from 0 - 300 yds your bullet would never higher or lower than 3.75" above or below your POA.

I made some assumptions before calculating:
1) 2" HOB
2) 62gr FMJ
3) .235 BC
4) 3100 fps MV

Atmospheric conditions and elevation would have some effects on the data. YMMV

ETA: My ballistics calculator doesn't work for meters, only inches and yards.

[ham385]

25M is pretty close for zeroing an AR, unless you're sporting an A2 rear sight, which you're not. The reason I point it out is I wonder if you found something online talking about zeroing at 25M. The A2 sight has a knob underneath it that allows you to zero at 25M, then you turn it back one click and you're zeroed for 300M. With other types of rear sights, 25M is not a bad starting point to zero there then move out to farther distances so you're at least on the paper when you do.

Is that the distance you expect to shoot at normally? If it is, then disregard. If you expect to shoot further, then try zeroing at 100M you should still at least get on the paper (hopefully). If you can't, then zero at 25M and then move out to 100M and zero there.

Did you build or buy from the factory? The reason I ask is the factory has a jig to make sure the front sight post, or rail, or gas block is straight on top of the rifle and not canted to one side. Most people who build have to eyeball it, which can be problematic. If you get out there and notice its badly canted, you may have to correct that before you are able to go any further.

Anyway, on to zeroing.

Your front sight post should screw into and out of the front sight base for elevation adjustments. You can use a nail, a bullet( Hollow points probably won't work), or a fancy tool they sell at multiple places for about $7-15. Or you can make your own fancy tool by filing notches in a spent casing. Usually, the threads are pretty long on the post, so I don't think you'll have a problem with it too high.

IIRC, looking at it from the top, clockwise will raise your point of impact(POI), counter clockwise will lower your POI. Likewise, on your rear sight, clockwise probably moves POI to the right, and counter clockwise to the left.

If you've never zeroed a firearm before, the process is pretty universal. There are nuances, but this is essentially what you want to do.

1. Fire a group of 3. Sandbags or anything else you can use to steady it help here. You need a respectable group to rule out shooter error, aka fliers. If you haven't established a group, keep firing until you do. At 25M, your gun should shoot a single ragged hole but if it's not, it's most likely user error. That's ok though, a 1 inch group should be enough to get by on.
2. Adjust your sights. If you have a 25m zero target, the lines will tell you how many clicks to move it. If you don't, you'll have to estimate the x and y adjustments to get it to the center. At 25m, I think it's something like 8 clicks per inch. (at 100 i believe it's 2 clicks per inch).
3.Repeat until you get a group on the bull.

Hope that helps!

[topsykretts]

Damn, 50 feet? Is there any way I can still use that range to zero my rifle? Can I print out some special targets that will appear to be the size of a target at 25m? Its the only range in Philadelphia that allows rifle calibers, to my knowledge. I did build my rifle myself, but the front sight is mounted on the top handguard rail and the handguards are pretty well aligned.. maybe off by a half a millimeter or less. Took me a lot of trial and error to get it that tight, too.

[Willie D]

SPAG isn't the best place to zero a rifle; only 21(?) yards, no benches, etc. but I suppose you can make do.

My rifle is zeroed at 50 yards (the so called Improved Battle Sight Zero) which is supposed to keep all of your shots within 2" of your line of sight out to 200m. The only time I shot it at SPAG I was hitting about 1.5" BELOW the point I was aiming at with the target all the way back.


I think I would try to zero to a similar low point and then fine tune whenever you make it to a longer range. If you adjust to hit exactly the point you are aiming at at SPAG, you'll be shooting very high 100m-200m ranges and probably still be a little high at 300m. Try making 2 marks on your target: one you want to aim at and one below you want the bullets to be hitting.


Good stuff here: http://www.ar15.com/forums/topic.html?b=3&f=18&t=328143

[he11zna]

First, you're going to have a hard time because it's damn near impossible to shoot "off the bench" at Philadelphia Archery and Gun. Good luck if you're trying to "zero" offhand (standing).

What is your intended use for the carbine?

Try to get to an outdoor range and actually shoot at distance.
Shooting reduced targets at short distances isn't the same.

[topsykretts]

First, you're going to have a hard time because it's damn near impossible to shoot "off the bench" at Philadelphia Archery and Gun. Good luck if you're trying to "zero" offhand (standing).

What is your intended use for the carbine?

Try to get to an outdoor range and actually shoot at distance.
Shooting reduced targets at short distances isn't the same.

Home defense/SHTF. If it were a SHTF situation, I can imagine it would be important to be able to accurately hit something at longer ranges.. not so important with a home defense situation.

See, the problem is I don't have constant access to a car, otherwise I would drive outside the city to an outdoor range. Are there any outdoor ranges that are accessable via septa in a roundabout way? Or any people on this board who go out of city, with wheels, to shoot their rifles? I'd be willing to pay for gas and lunch if I could tag along just one day to get it sighted in, after that I can practice at the phila. archery n gun club.

[ham385]

Short answer, you can get close to zeroed at 50', but probably not perfect.

Long answer follows (and it's late, so no guarantees on my math):
1 moa is 1.0472" at 100Yards or .17453" at 50'
Each click is probably 1/2 moa, depending on the sight, so halve that number.

roughly 11 clicks per inch at 50'.

but you also need to account for ballistics. At 50' you may be impacting below the sights (remember, there's about 2 3/4" between the sight and the muzzle), and as you go further out, depending on the bullet and velocity, the bullet will actually rise in an arc (to bring it in line with the sights) before gravity starts to win and the bullet starts to fall.

What this means is if you are able to move your sights enough to zero at 50', at 50yards you will probably hit about 2"-3" high, and at 100yards you will probably hit 5-7" high. I'm just guessing at the numbers, but you get the idea.

Knowing this, you can fudge your zero to get close to where you want to be for the range you intend to shoot at, but you will have to fine tune when you do get a chance to use it at the regular distance.

If it were me, and this were my only opportunity, as suggested previously by willie, I would still try to sight in with goal being impacting about 1.5" - 2" directly below what I aimed at.

Worst case, that should get you closer than you would be and make it easier when you do finally get to a longer range. I'd offer to help but you're on the wrong side of the state.

Oh, and if you can't find a bench and sandbags there, lay down on the ground. It's a lot more stable than standing.

[he11zna]

Home defense/SHTF. If it were a SHTF situation, I can imagine it would be important to be able to accurately hit something at longer ranges.. not so important with a home defense situation.

See, the problem is I don't have constant access to a car, otherwise I would drive outside the city to an outdoor range. Are there any outdoor ranges that are accessable via septa in a roundabout way? Or any people on this board who go out of city, with wheels, to shoot their rifles? I'd be willing to pay for gas and lunch if I could tag along just one day to get it sighted in, after that I can practice at the phila. archery n gun club.

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