How do you zero your service rifle?

[Quintin Likely]

I'm going to another 300 yard reduced match tomorrow. The first time around, my zeroes were totally screwed up. What I thought was good enough to whack a 12x12" steel plate off a bench at 200 yards was about 3 minutes too high in the offhand, I reckon. Work and other things hasn't left me time to get back out and work up a proper 200 yard zero, so I'm going into this one with my pants down.

My question is, knowing that all rifles and loads are laws themselves, is there a good rule of thumb for a "close enough to get on paper" 200 yard zero? When I left the match last time, my sights were pretty decently on for 300 yards, even though I was all over the place, but I'm gonna assume that was lousy position on my part. So, let's say my sights are somewhat on at 300, how much do I need to dial down for 200? I'm shooting a service rifle AR, BTW, a Rock River NM A2. And should all my adjusting be from the rear sight only? I haven't touched the front post since I got the upper.

 

[Jon Coppenbarger]

I would start about 1 moa to 1 1/2 moa down and go from there.
Since I do not know how your rifle shoots combined with your loads.

But remember this and its important since most likely you will get only 2 sighters MAKE sure your first sighter in a good shot by you and adjust from there.

After that shot or any shot you should be able to adjust your rifle to the center with only one shot.
Remember this from the edge of the black on any nra highpower target it is 3 moa to the center of the black. So for example if your first shot is lets say a mid ring 9 at 2'oclock on the 200 yard SR1 target with only the 9,10 and x ring in the black you would move your sights this amount.
1moa you would catch the inside edge of the 10 ring with maybe a few shots on either side depending on how well you hold.
1 1/2 moa should get you inside of the 10 ring mid way
2 moa should get you into the x ring
every 1 moa angle for sake of argument with nunmber freaks will get you right close to 2" of movement at 2oo yards.

What you have to remember that you might have a different point of impact in different positions like going from standing to sitting and to prone and that ok. mine are close to the same but after each string this weekend please wright down what your zero's were for every string and when you go back you can put that dope right back onto your rifle and get it close.
I will go to my zero's I have noted for that range and conditions and start from there and if something seems wrong after taking each shot like for no reason I amout in the edge of the 10 at 3 or something like that I will check myself as i may be canting the rifle alot more or at all of something like that and fix it. Like at a match a few weeks ago in sitting my sighter's
were out to the left and I dialed in about a moa for the low light coming at a angle this time of year but realized I was canting my rifle real bad also. I corrected the cant to what it should be normally and for me thats like close to Zero and fired my first two shots and during my mag change and they were good shots and finished my string. did that on both strings and it came up a clean 200. Now I did not do that in the leg match at perry this year and it cost me leg points as they were out at 5, mistakes you leran not to make again.

Gotta run to work so good luck and let us know how you did.
Jon

 

[Quintin Likely]

We're slowly getting there...

Last time out, I shot a 290-1X. This time was 404-1X. Not great, but I'm proud of them, by Gawd.

Jon, I dialed down about 1.5 minutes from my 300 yard slow prone setting in the 200 yard offhand and ended up with an 8 and 10 for sighters, I believe. Today was a really nice and calm day, wind-wise, didn't do any
corrects for windage until the sitting 3, and that wasn't but .75 MOA right, IIRC.

Learned a lot more today too, like the transition from standing to sitting is gonna need a lot more work. After the match, some guys helped me out with my offhand and sitting positions too, so I've ironed a few bugs out. If only you could see the big you-know-what eating grin on my face right now. Next match is November 6th.

Thanks again.

 

[Quintin Likely]

I just noticed something tonight. After the match, some guys helped me sort out my offhand and sitting positions a bit. I fired a few shots in sitting at 300 yards, then ran out of ammo, so I went home. I just checked my rear sight now, and it's bottomed out. As low as it'll go. Am I missing something here?

With the sight one click above bottomed out, in sitting at 300 yards, I was shooting some pretty consistent 9s and 10s, with a low 8 here and there.

So, that means that I dialed down about 6 clicks from my previous match, where I've kept the sight settings I used there until yesterday, for 200 yards, then at first during the 300 yard string, I dialed up 6 clicks, shot the match, then afterwards, based on another shooter spotting me, I came down 3 or 4 and right 2, IIRC. Does this mean my rear sight was way high for the 300 yard line from my last match? I do know I had a stronger showing at 300 this time than last time.

Why in the world would my rear sight be bottomed out and still be shooting on paper at 300 yards? I'm shooting 77 Sierras, BTW, and it was a pretty calm day, but that still doesn't quite add up to me. I guess I need to get out and work up some solid 200 yard zeroes next, but man, I still don't get how that worked out.

 

[Bwana John]

For my M-1a I move the front sight while zeroing windage, so that the rear sight is right on its calibrations. I reset the elevation on the rear sight to zero at what ever distance im zeroing at. (200,300,600ect) . On my AR I move the front sight while zeroing for elevation until it works with the rear for the range Im at, and for windage I paint a hashmark on the windage dial after zeroing the rear sight.
Once the range and windage is properly zeroed, I just dial the sights to where they should be. At the end of the match when Im cleaning I try return the sights to battle zero. (0@200yds, no windage)

 

[Grump]

Isn't bottomed out on an AR, using the small aperature, supposed to be your 300 zero anyway?

Some of us are renegades and like to get either 2 or 4 clicks lower than 300 on the elevation drum. Then we can dial down to a 200- or 100-yard zero with the small aperature.

If you don't like being bottomed, just raise your front sight a few.

 

[Quintin Likely]

Grump, my upper has a hooded rear aperture only. If I ever shot at 100 yards, I'd like the option to dial the elevation drum downwards to get there. I think I see what I've done though, I haven't messed with the front sight since I got the upper, and it's bottomed out right now as it is. I think one revolution up will give me some room to play with at distances less than 200 yards.

 

[Steve Smith]

Grump, no offense, but please keep the "renegade" comments out of a competition specific conversation. It really confuses matters.

Quentin:
First of all use the search engine and search for "mechanical zero" cross referenced with my name. There you will find how to set the mech zero for your rifle. Once you have that set, I would suggest this:

1
Bottom your rear sight. Bench the gun if you must and fire it at wreal target (200 yard Highpower target SR1). Be sure to have a consistent point of aim. Fire a group and then take a look to see where you hit.

If you are low:
Use a M16 A2 front sight tool and lower your front sight. Your sight should have a bevelled top plane and the bevel should be away from you when you're behind the gun. From now on only move the front sight in complete revolutions. One rotation of the front sight will change your POI 5 MOA. So, as I was saying, move your front sight DOWN one rev (or until the top plane is away from you whichever is less).

If you are high:
Raise your front sight by one rev.

2
Fire the gun again, from a rest if you must, and note the impact again. Now turn the rear sight up or down and fire untill you hit the center of the target. What you WANT is for the 200 yard elevation to be within 15 clicks from the bottom (elevation mech zero). If it is not, readjust your front until it is.

3
Now, pull out your databook and a pen. Write in the front the serial number of the gun and 200 yards. Then count the clicks on the rear sight from your 200 yard zero to Elevation Mech Zero and WRITE THE NUMBER IN YOUR BOOK next to the S/N and 200 yards.

4
Ok, now you have a 200 yard zero. From here you should be able to go "anywhere" with the rifle and get a start. To go to 300 yards, you just add 3 MOA. To go to 600 you add 9 MOA. That will get you on paper and more than likely in the black. After that you can just tweak it a little and you'll be right there.

Good luck and keep us informed.

Steve

Edited to un-ass myself.

 

[Grump]

Steve: Okay, some of us are "unconventional" and might not do it precisely the way the USGI TMs instruct. Now I'm confused, how does "renegade" confuse matters? I can truly be clueless on social cues, donchaknow...

Correction: I think you really meant to say that if your group is high, you'd want to lower the front sight.

Glad to see you're "back," although your location suggests that "back" means you get to access a computer once in a while. Thanks for your efforts. I was doing competitive speeches in high school, calling for NO safe harbor for terrorists and no international borders should be allowed to keep our troops from flattening training camps. 1977! Too bad it took a SECOND strike on the WTC to get the nation and its leaders on _our_ side...

 

[hipwr223]

if you are high you need to raise your front sight.

 

[Steve Smith]

Ever put so much detail in the description that you forgot a simple point?

I edited it to correct my dumb-ass post.

Grump, what I mean is that the "little aperture/big aperture" stuff doesn't apply to this conversation.

 

[Jason Demond]

I zero my rifle locked in the prone position. Everytime I zeroed off a rest, I'd shoot 3" low.

 

[Steve Smith]

I think most people zero from position once they know what they're doing. I think it's helpful for a beginner to use a bench to get the gun pointed in the right direction.

 

[Quintin Likely]

Steve...

Thanks for the excellent explaination. We're kinda in the off season around here, so I'm gonna work up some loads whenever my reloading stuff gets here.

Y'all stay tuned.

 

[Dave P]

"Last time out, I shot a 290-1X. This time was 404-1X. Not great, but I'm proud of them, by Gawd. "

40% improvement is wonderful - keep it up! And 404/500 = 80% which puts you in the Expert classification, I think!

DAve

 

[Quintin Likely]

It would have...

...if it were a national match course of fire. The local shoots here are 80 shot regional formats. But I'm working on it...

 

[Grump]

Jason, you shooting an AR without a float tube?

In smallbore, I once had about 3/4-minute difference in zeros between prone and standing. Our newbies can work with this once they can call their shots reliably...and get confidence in what they see when the shot breaks.

 

[Jason Demond]

Sorry Grump, I was talking about an M1 Garand.

 

[Grump]

I was wondering because of the sling tension variable. IME, it's worst with M16A1-types, and about even with M1/M14 and ARs with medium-heavy barrels/HBAR format. Never shot a float tube gun, but I'd expect it to be as immune to sling tension as my free-floated smallbore gun. "Hardness" of position, however, can still give me only about 1 minute of zero variation--looser holds recoil a bit more during barrel time and tighter holds hit a bit lower.

 

[Steve Smith]

It's not unusual to have a 3/4 minute change between standing and sitting.

 

[OtG]

Steve Smith

It's not unusual to have a 3/4 minute change between standing and sitting.

Why is this? Is it because of head position, or sling tension?
Or something else?

 

[Jon Coppenbarger]

it could be for several reasons and it all depends on what you do and what you have done.
Now if you are normal and do it by the book you cant inboard for off hand and out board for sitting so that alone would be a different zero. then you might also be looking more straight down the sights in off hand and with your head bent over a little more in sitting.
You add that all up and you get a zero change.

I am really a exception to the rule above as my zero's are the same between the two but that came from alot of work ( years of trying things)and with the rifle just fitting me right to allow this to happen. Does not happen on the norm.
But steve can tell you I am weird anyway. LOL

 

[hipwr223]

From off hand to sitting I always have 1 MOA of left correction. When you shoot with a cant, with the AR service rifle in particular, it requires an adjustment for windage in a more dramatic sense. The AR sights are so high relative to the axis of the bore that even slight canting of the rifle will create noticable changes in POI on the target. If the angle of your cant is not consistent the amount of POI shift will never be either.

 

[Steve Smith]

I am fortunate to only have about a 1/2 MOA change in windage across the course, and 3/4 MOA in elevation from standing to sitting. It just happens depending on how you hold the rifle.

 

[wanderinwalker]

Cant? What about canting? You lookin' at me?

My zero change from standing to sitting is 1 minute up and 3 left. Major, major cant. But I am awkward and this is the only way to fit me to the rifle. Prone rapid involves coming up 2 minutes from sitting and right 4 minutes or so. (I actually have it just written in clicks in my notebook, so this is going off of memory.)

With enough practice and consistency, I don't think canting the rifle is a bad thing. (Kind of like the story I read for English class the other day where the author described death as an evil thing to be avoided, but I digress.) It makes me more secure and my zeros don't shift. It just boils down to what you can and can't live with in the end.