Factory Zero

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g19glock1

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Noob here with a question. I just purchased a new M&P 15 last weekend, an am planning to zero it with the factory iron sights tomorrow afternoon. I am wondering if they are factory zeroed as the rear sight was not centered but way to the left of center on the Magpul sight.

I hope I did not screw it up as I moved it to the center line. I am sure that I can zero it, but just had the question in my mind.

That being said, I have read a number of posts regarding sighting in and some say zero at 25 yard for a 100 yard zero. With my M-14 while in the military (US Army 69 - 73) we zeroed at 25 for a 250 yard zero.

Any insights?
 
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The AR15 features a rather high sight offset and because of this Convergence can be a problem if sighted for 25 yards. My personal preference is to zero the sights at 50 yards and doing this will result in the flight path of the bullet crossing the zero point somewhere between 200 and 250 yards depending on the bullet and load used. At 100 yards the shot will only be about 3/4 inch high and for me that isn't a problem.
 
I zero depending on the expected usage of the rifle. I zero my 6.8 SPC 1.75" high at 100 yards for hunting. That allows me to hold dead on out to 250 yards.

Scooter's 50 yard zero works just fine for a .223 for general use with mil-spec ammo. However, heavier or lighter bullets may need to be zero'd differently. Again, we're back to expected usage.
 
g19glock1 said:
Noob here with a question. I just purchased a new M&P 15 last weekend, an am planning to zero it with the factory iron sights tomorrow afternoon. I am wondering if they are factory zeroed as the rear sight was not centered but way to the left of center on the Magpul sight.

I hope I did not screw it up as I moved it to the center line. I am sure that I can zero it, but just had the question in my mind.

That being said, I have read a number of posts regarding sighting in and some say zero at 25 yard for a 100 yard zero. With my M-14 while in the military (US Army 69 - 73) we zeroed at 25 for a 250 yard zero.

Any insights?
Click to expand...

I believe they are factory bore sited which is a good place to start. I did exactly as you did, but my lgs that I purchased it from was kind enough to re-bore site it as a courtesy.
 
There are multiple thoughts on how to zero the AR 15.

1. The military use the 25 Meter zero for carbines with the carry handle sight. Zeroing at 25 meters with the elevation drum set on (6/3) would give you a 300 meter zero.

2. Improved battle sight zero - similar to the zero above requiring a carry handle sight, only it gives you a 50 meter zero with the small aperture, but keeps the elevation drum working for the 300 to 600 meter settings.

3. 50 Yard zero. Using this zero, you will be +/- 2.5 inches out to around 250 yards. Without a method to adjust for elevation at the rear sight, this is what I use when shooting different distances out to 300 yards.

4. 100 yd zero - If you are going to shoot at 100 yards and want the best grouping at that distance, then zero for 100 yards... With this zero, you will be low at any distance other than 100 yards.
 
Mine was zeroed at 50 yards out the box. Not sure if factory done or pre-sighted at the store however. Preferring the 50 yard zero, I left it as is.
 
Thanks all, I will have to see if I screwed up the factory zero. I will report back. I am going to go for 1" high at 50 yard zero.

I will report back when I get it done.
 
I seriously doubt the factory "zeros" any guns. Too time and ammo consuming... I submit they install sights and adjust them to a predetermined adjustment per SOP. When I went through the armorer's school, I watched the shooters shoot for function but not sight adjustment or accuracy. They spent about 30 seconds on each gun...
 
ken158 said:
I seriously doubt the factory "zeros" any guns. Too time and ammo consuming... I submit they install sights and adjust them to a predetermined adjustment per SOP. When I went through the armorer's school, I watched the shooters shoot for function but not sight adjustment or accuracy. They spent about 30 seconds on each gun...
Click to expand...

Thanks, I will probably try to print shots on paper at 25yds, adjust as necessary then move back to 50 to make the final adjustments.
 
I honestly never paid attention. Any time I go to zero a rifle, iron sights or optic, I start at 25 yards to get it close on paper and "walk" it back to whatever range I want to zero it at. If 50 yards, I stop there. If 100 yards. I stop at 75 and finally 100.

It's easier if you are doing a scope in a rest. Shoot once. If the rifle moved, put it back on your point of aim and adjust your windage and elevation to point the cross hairs or reticle to point to your actual point of impact. That usually gets you pretty close if not right on where you want the round to go. That way you are wasting as little ammunition as possible. You just fire another round to confirm your adjustment.

I suppose one could use the same method for iron sights, depending on their design. With MSRs, it should work but with something like a Marlin 336, not so much.
 
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You don't need any fancy equipment to "bore sight" an AR (or any bolt action rifle for that matter).

Remove the bolt carrier group and put the upper on a solid rest (sandbags are ideal but not required). Sight through the bore on a small object (4-6" in size) 50 yards distant (a bull on a target is nice to have, but any small object that you can clearly distinguish on it's background will do, such as your neighbors front porch light :)). Without disturbing the upper, sight through the iron sights. Are they aligned with the sight picture you see through the bore? If not, while holding the upper as still as possible, move the sights to line up with the sight picture you see through the bore. This may take several retries, but it should get you very close.

I've been using this technique for years and I really get a chuckle when I look at all the "equipment" you can buy nowadays to bore sight a rifle!

Lou
 
All I can say is WOW WOW WOW, just got done zeroing my new MP-15 and cannot believe how happy I am with this firearm. Zeroed at 50 yds and getting a less than three, but more than 2 " grouping, in shots of three. I love it. This is my first experience with the AR type of rifles.

When I was in the service 68 to 73, we had M-14's, which I also loved, wish I had one now. My base started getting M-16's as I rotated out of the service, so I never got to fire one.

What a joy to fire an AR.

I used up about 45 rounds zeroing, but now have a firearm that I am comfortable with, knowing that I am gonna hit what I aim at, as long as I do my part.

Thanks all for your words of enlightenment and encouragement.

Merry Christmas to all.

Kim
 
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g19glock1 said:
All I can say is WOW WOW WOW, just got done zeroing my new MP-15 and cannot believe how happy I am with this firearm. Zeroed at 50 yds and getting a less than three, but more than 2 " grouping, in shots of three. I love it. This is my first experience with the AR type of rifles.

When I was in the service 68 to 73, we had M-14's, which I also loved, wish I had one now. My base started getting M-16's as I rotated out of the service, so I never got to fire one.

What a joy to fire an AR.

I used up about 45 rounds zeroing, but now have a firearm that I am comfortable with, knowing that I am gonna hit what I aim at, as long as I do my part.

Thanks all for your words of enlightenment and encouragement.

Merry Christmas to all.

Kim
Click to expand...

Well, if you would like an M-14 like rifle, Springfield Armory sells the M1A. Of course, the price is kinda steep compared to the rifle you just got but is pretty much in line with the price of Ar-10 style rifles in .308/7.62 NATO.
 
stwings said:
Lots of zeroing info here:
AR-15 Zeros and Trajectories
Click to expand...

Thanks for posting the link, great information...

OP, I'm sure the factory does not sight in each rifle, but rather just fire the rifle to ensure function. They probably initially sighted in a rifle with the sights they put on all of them, and then just set the sights in that pre-set position going forward.

My experience with my Colt ARs, and M&P 15 is that they are pretty close out of the box.
 
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