Correct way zero your AR Service Rifle for NRA/CMP Competition
Forget all the IBZ military stuff. This is KD competition shooting and you should zero for the range you are shooting at, with the ammunition you are using for that range.
To establish an initial zero, you put your rifle rear sight to mechanical zero - set your rear windage to zero wind and bottom the rear elevation out. Leave the front sight alone.
Rear windage:
Rear elevation - all the way down to the bottom till it wont go lower:
Come up one click on the rear sight to get rid of that bottom click which may be false and then come up a minute or two. It does not really matter how many, just that you are off the bottom. I use one minute, but you can use something different. This is to make sure that you have some adjustment in case you are shooting a little different ammunition, or maybe shooting a reduced course match at 100 yards.
Don't put any marks on it yet. Wait until you actually zero the rifle.
Go to the range. It's best if you can do this at 200 yards, as that is where you start the first stage of a HP match. If you don't have access to a 200 yard range, you can do this at just about any range if you know how to use a ballistics program and you have some basic data. However 50 yards is a good place to start. If you are shooting typical short range AR ammo, 50 yards will put you in the center at 200 yards. What is typical? A 69 or 77 grain Sierra bullet or equivalent from Hornady, Nosler, Laupa or Berger. 2900 fps for the 69s and 2750 for the 77s.
At 50 yards, you are going to be within a 1/2 inch of the center of the target with either 69s or 77, and at 200 yards that is zeroed.
You can get a scaled 200 Yard SR Target for 50 yards from
Ray-Vin. Print it on buff/tan colored paper to avoid white paper glare when you shoot at your target.
Figure out what sight picture you are going to shoot. What ever you do here, is what you are going to do at full 200 yards. Center of Mass, Line of White or 6 O'clock does not matter, as long as you do the same on the full distance. Shoot a couple of shots in a group and then
make all your adjustments on the front sight to zero. Remember that elevation and windage directions are the opposite on the front sight. Elevation increments for the front sight is 1.25 minutes per notch which translates to ~.625 inches at 50 yards.
Use one of these for the elevation.
Do the elevation first. If you have a windage adjustable front sight base, do that now. If not, you need to adjust your windage on the rear sight. It's no big deal if you don't. The main benefit of a windage adjustable front is that you will have the maximum about adjustment available on your rear sight. Around here that may not be a big deal, but if you are shooting out west, where it blows like crazy then that can be a good thing.
If you're close, but not quite zeroed, you can use the rear sight to cleanup your zero. The movements are much finer than the front sight and sometimes I just get in the ball park on the fronts, and then use the rear to make it perfect.
Now you mark your sights with a line. I use there Sharpie paint pens, but nail polish works well too. Pick one color. I like Red for my 200 yard zero.
From my 200 yard zero I come up three minutes and I put another line. This time orange. This is going to be for the 300 yard line. Ideally you should go and zero at 300 yards, but it's not really necessary. When you do actually shoot at 300 yards, make a note of where you were in relation to your mark. Maybe something like 1/2 minute down from orange mark. This will be your actual zero. If it's exactly on the line then you win a booby-prize. I find that my zeros from day to day wander around within a click or two.
From my 300 yard orange mark, I come up 9 minutes and then draw another line. This time it's yellow. This is my 600 yard reference line. I've actually changed ammo though, and am shooting some kind of 80gr bullet. I don't shoot the 77s across the course. Again, I only use this as a reference for my zero. My real 600 yard zero might be 1 minute up from yellow mark.
The reason I do this is that it's too easy to lose track of clicks. If you are counting clicks, you are going to step on it big time at some point. It's much easier to go to a rough reference line and then make a fine adjustment. If you are solid on your zeros, you can adjust the paint lines where the zero actually is. That is the ideal way, but as I said, my service rifle zeros move around a little from one match to the next.
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