M&P15A Sighting in

[Cessna_Driver]

I now have a new 15A. I took it to the range Saturday where I checked out my wife's new "G" brand .40 and ran several magazines worth of .40 out of my M&P40C, too.

I shot the 15 at 15 yards since I had to wait to change out targets. My pattern was on target for windage but 6" below the bullseye. I found my front sight was at its lowest setting. Unfortuantely, I didn't have a scope, so at the 75 yard range I couldn't see where I was hitting.

My question here is, should my pattern be 6" low at 15 yards? That doesn't seem correct to my thinking.

Thanks for any help.

 

[Cessna_Driver]

I now have a new 15A. I took it to the range Saturday where I checked out my wife's new "G" brand .40 and ran several magazines worth of .40 out of my M&P40C, too.

I shot the 15 at 15 yards since I had to wait to change out targets. My pattern was on target for windage but 6" below the bullseye. I found my front sight was at its lowest setting. Unfortuantely, I didn't have a scope, so at the 75 yard range I couldn't see where I was hitting.

My question here is, should my pattern be 6" low at 15 yards? That doesn't seem correct to my thinking.

Thanks for any help.

 

[torrejon224]

First, in order to get a good sighting in done, it needs to be at either 50 or 100 yards. Suggest you check out the AR15 forum for several excellent links to getting it done either with or without a scope.

 

[JayCeeNC]

Remember that the sights sit above the bore about 2.5". It will hit low at short ranges. Like torrejon said, sight in at 50 or 100 yards.

 

[tom turner]

Hi,

I'm having to run out for the evening and won't be home until late.

The link I was going to post is down so I pulled up a file I saved and converted a chart to a JPG for you.

There are three ways to sight the M-16, the Marine technique, a new Army way, and this chart.

Marines zero at 300 yards

The chart I'm posting zeros at 50 and then the rainbow comes back down at about 225 yards, depending on barrel length. This is the way I zero mine.

Thus, if you want to save time and ammo, use the chart's 25 yard trajectory and you'll be really in the ball park.

Also some zero at 30 yards, which, IIRC, gives you a 200 yard zero too. Or . . . is that 30 METERS?

In any event, this will get you started, and also give you some clues of how to use key words on Google to find out what I'm talking about.

PS: There are also a couple of good forums for M4s and such . . .

Hope this helps,

Tom

Gotta run . . .

 

[Cessna_Driver]

Thanks for the feedback. I had forgotten to take a scope or binoculars with me so I wasn't able to see the target hits at 75 yards. I tried three different sight pictures and one of them worked -- maybe it was the correct picture that actually was pretty close. I will go out next weekend, this time prepared and work it at 100 yards. Everything I hear is that these rifles are quite accurate. I know they are fun to shoot!

 

[shawn mccarver]

Originally posted by Cessna_Driver:
I now have a new 15A. I took it to the range Saturday where I checked out my wife's new "G" brand .40 and ran several magazines worth of .40 out of my M&P40C, too.

I shot the 15 at 15 yards since I had to wait to change out targets. My pattern was on target for windage but 6" below the bullseye. I found my front sight was at its lowest setting. Unfortuantely, I didn't have a scope, so at the 75 yard range I couldn't see where I was hitting.

My question here is, should my pattern be 6" low at 15 yards? That doesn't seem correct to my thinking.

Thanks for any help.

The A2 rear sight has a provision to get a preliminary zero at 25 meters by setting the elevation adjustment knob one click below the standard setting. Set windage at this distance and then zero elevation. In theory, when you move the sight back up one click to its base setting, you should be on at 100, I believe. This method might not get you exactly on, but it gets you in the ball park, and then you do precise adjustments at your distance. I am sure an internet search for zeroing the AR15A2 will yield good results and a better description of this method.

 

[3-gun]

Go with this.
IBZ

 

[tom turner]

Originally posted by 3-gun:
Go with this.
IBZ

That chart would be great with a full-length rifle barrel, but the trajectory might not be optimum for an M&P15 carbine.

It all depends on the distances where you want to minimal variation from pure zero to be, of course.

T.

 

[ENH]

I found my front sight was at its lowest setting.

For future reference move the rear in the direction you want the bullet impact to move or the front sight in the opposite direction .

 

[3-gun]

Originally posted by tom turner:

Originally posted by 3-gun:
Go with this.
IBZ

That chart would be great with a full-length rifle barrel, but the trajectory might not be optimum for an M&P15 carbine.

It all depends on the distances where you want to minimal variation from pure zero to be, of course.

T.

16" or 20" out to 250 yds it's not going to matter.

 

[Cessna_Driver]

Originally posted by ENH:

I found my front sight was at its lowest setting.

For future reference move the rear in the direction you want the bullet impact to move or the front sight in the opposite direction .

I didn't mention that my rifle has the rear peep sight and not the A2 sight. I am going to return to the range with a spotting scope and sight in the rifle at 100 yards. I'll see what happens there.

Thanks to everyone for the feedback.

 

[tom turner]

Hi again,

You didn't say whether you are sighting to hit high at 100 yards or not, so I can only assume you are sighting it to shoot at point-of-aim at 100 yards. Not good, IMHO.

Decide the anticipated ranges that you'll want outstanding P.O.A. accuracy from your gun and set it up to do this.

For instance, I want mine to shoot at P.O.A. +/- two inches . . . and use a chart that gives me this accuracy from about 8 yards out to 260 yards.

The bullet crosses the dead zero spot at exactly 50 yards, rises two inches maximum and crosses the dead zero spot again at about 225 yards.

This means you can test it's zero by using targets at either 50 yards . . . or 225 yards. BUT WHY DO EITHER?

The chart I posted earlier shows these settings, as well as the 25 yard mark being 1.2" low. Thus, to save time, energy and money at the range, I sight in at 25 yards to be 1.2" low.

I can see where it hits fine, and don't have to wait long periods of time for the range to go cold . . . and then have to walk nearly 1/8" of a mile to change/view targets. MAKES SENSE TO ME.


Thus, I zero much faster! Then, once this is done, I'll shoot targets at 50 and 100 yards to verify what I already know I'll be seeing.


JUST AS IMPORTANT . . . the push of the wind on the bullet is negligible at 25 yards, but not so at 100. So if you are facing winds of even moderate amounts the day you sight in, you may sight for windage incorrectly at 100 yards.

Properly zeroed at 25 yards for perfect POA at 50, if the wind is blowing as you shoot at 100, look at your wind drift charts for your specific bullet vs. the wind speed, and you'll start learning how to aim to correct for various wind problems . . . something that good riflemen learn to do.

Just to go out and sight at 100 yards without learning this stuff is . . . well, like pissin' 40 cents in the wind each time the gun goes bang.

No offense intended . . . just trying to help you become a better rifleman and save you some money too.

Whatever you decide, have fun. These little rifles are cool!

Tom

 

[Cessna_Driver]

Good info Tom Turner. I bought a box of 500 rds of reloaded ammo but I think I'll buy some factory stuff so I can be sure of the ballistics. Sighting in at 50 yards like you metion sounds like a good way to go. I did notice those little .223 holes are hard to see, so 50 yards should be much easier to spot with binoculars.

My original post discussing where the POA was at 15 yards was inaccurate. I was aiming with the black area of the target at the top of my front sight. Where I should have been aiming was precisly at the X in the center of the target. I was aiming like one would at say 100 yards. The way I was aiming put my POA about 3 inches below where I was actually aiming.

I'm going to take your suggestion of 50 yards to sight it in and then see if I get the expected 1.7" high at 100 yards. I may wait a week or so, though. I ordered an EOTech sight. I work for L-3 Communications and can get one for 1/2 price so I thought I'd go for it.

Thanks,
Bill

 

[conchmariner]

I've been having a similar problem with my M&P15, and it still shoots low at 50 yards with the front sight as low as possible and the rear sight as high as possible. FWIW I had the range master try to sight it for me since he's a much better shot - his conclusion was that I need a lower front sight. The shop where I bought the gun and sight will trade me a new sight, but the owner told me he thinks these guns should be zeroed at 100 yards, not 50 yards. So now I'm really confused.