Scope holding zero... realistic expectations?

[Religious Shooter]

Last 3Gun match I shot I wasn't doing so well with the longer targets. The kicked up dust was indicating that I was shooting lower than expected. A couple of days later I went to the range to confirm my "zero" and sure enough it wasn't shooting where it was supposed to.

I've had this experience (loosing zero by 2-4 MOA) with an IOR, Meopta and TR21 while using YHM and MSTN/PRI extended rail mounts and IOR, Leupold and Burris XTR rings.

I've ALWAYS thought that the friggin' scope and mount should retain zero. Period.

But is this a realistic expectation?

A lot of people I know travel to a big match and reverify their zeroes at the match. Why do this unless they too have had shifting zeroes? I read that some people who shot the BARC match were having problems with their zero.

Does that mean that scopes shifting zeroes is actualy a fairly common occurence?

[Dan Sierpina]

Prior to my last match, my rifle case (soft case) tipped over and landed on the scope. A couple days before the match, I checked my zero, it was 3 inches higher than it was set for. The match was a short range match, but, the rounds would have gone over the top of the plates, etc.

Checking your zero at a match, if you can is a good idea. Better to know if things are what you expect. Some years ago, at the Masters, a shooter that lives in New Mexico showed up in nice humid Illinois. Her wood stocked XP100 was shooting no where close to where it did at home.

Zero's can and do shift for a number of reasons, including altitude.

[kurtm]

I think that optics just don't like you! After all you are "religious" and scopes are the work of Satan! Just go back to Iron sights and all will align in the world.

Actually this has alot to do with how an AR barrel fits into the receiver. If the nut isn't tight OR the receiver face isn't square the barrel will jump around in the receiver causing "wandering zero". I have seen this in many ARs over the years and the cure, Just like Colt used to do is install the barrel with blue Loc-Tite between receiver and barrel extention to fill in any gaps and loose spots, this helps with the wander......But in the long run just shoot iron ( note: this will also happen with an iron sighted AR rifle, except the shooter tends to blame themselves instead of the rifle )

The other cure is to get a J.P. upper as these things are press fit and there is NO wobble I haven't seen a J.P. wander yet! KURTM

[Bronco]

If available I'll always check my zero, haven't had to change it yet for 3 gun. You mentioned extended mount, if this is one of those that attaches to a rail on the hand guard and the upper reciever (bridges the barrel nut) than I'd bet that is the problem. Have seen these wander all over the place.

[Carbon]

I have never had a zero shift but I always use a JP rifle at matches too. Kurtm may have something there. I also use a one piece scope mount like an Armalight or US Optics to be on the safe side.

Now to be fair I have missed like crazy at matches with Iron sights and different scopes over the years only to go home and find out that the rifle is right on. But my Weaver 1-3, Trijicon's, iron sights ect. have never moved.

What does happen is changes in conditions. My buddy Carlock has taught me to pay attention to wind, elevation ect. The other thing that happens at matches is a different shooting position from what you practice at home. Different holds do effect zero.

Basically every time I have messed up at a match it's been my fault not the equipment.

Carl

[EricW]

FWIW,

I have a Meopta that's on it's way back to Meopta b/c it has about 8" of parallax @ 100 yds and I can discern no range between 50 and 350 yards where there is anything but a hellacious amount of parallax. Good scopes do go bad occasionally. I have one.

[George]

Kurt is on the money about why and what to do about it. When I usta' campaign a custom shave-top AR I would check the zero anytime I traveled it, or it even got banged about real hard.

Now that I have a JP CTR upper with an ACOG bolted right to it with just a tad of blue loctite, I don't bother worrying about zero wander anymore. Once it's zeroed it doesn't wander, no matter how hard a beating it takes :-)

[benny hill]

Tried iron sights & they did'nt lose zero but my eye lost zero & wandered all over the place. I'm hopeless

[Merlin Orr]

"wandering zero"....? Yea, that must be it! Thats why I missed (and continue to miss). That has to be the reason.

[PacMan]

I've ALWAYS thought that the friggin' scope and mount should retain zero. Period.

But is this a realistic expectation?

Actually YES, as long as I don't monkeying with the mount and all the screws are tight. With regards to verifying zero after arrival at the match, there are other reasons such as elevation and temperature differences. With the same load, my rifle would change about -1" going from 7200 ft elevation & 30 degrees to 1000 feet (Mesa, AZ) and 75 degrees, just as the ballistic program calculated.

Edited July 4, 2007 by PacMan