Unusual zero problem

[Kikn]

I was bored and went to the range today.

I started out and checked my zero. Shit a5 round group at 100 yard's shots hit about 2" high 3 bug holed 1 pulled and the other next to the other 3. So far so good keys move to 200 yards fired 3 shots one bull and the other just a tick above. All and all good to go to the other range.

So i pack up my gear get in the truck and hit the long range. I get there unpack and promptly missed every target. I can't figure out what exactly happened i put that gun up and pull out my other grendel. I make hits from 300-800 yards no problems... eventually i pull out the problem gun which is a relatively new build. I finally figure out that my misses are way short...as a mater or fact so short my new zero is at 500 yards...it's pretty dead on there hit the 6" swinger 3 times in a row with out any elevation adjustments.

The gun wasn't dropped using same factory Hornady ammo. Nothing is loose at all. Any thoughts on what could have happened ?

[LR1955]

I was bored and went to the range today.

I started out and checked my zero. Shit a5 round group at 100 yard's shots hit about 2" high 3 bug holed 1 pulled and the other next to the other 3. So far so good keys move to 200 yards fired 3 shots one bull and the other just a tick above. All and all good to go to the other range.

So i pack up my gear get in the truck and hit the long range. I get there unpack and promptly missed every target. I can't figure out what exactly happened i put that gun up and pull out my other grendel. I make hits from 300-800 yards no problems... eventually i pull out the problem gun which is a relatively new build. I finally figure out that my misses are way short...as a mater or fact so short my new zero is at 500 yards...it's pretty dead on there hit the 6" swinger 3 times in a row with out any elevation adjustments.

The gun wasn't dropped using same factory Hornady ammo. Nothing is loose at all. Any thoughts on what could have happened ?

KK:

You are right! You sure did 'shit' a 5 round group. Is that your spell checker? He,he.

What was your come up between 200 and 500? Chances are it is around 8 or 9 minutes. If so, nothing is wrong and all you need to do is zero it at farther distances and record your zeros.

LR55

[NugginFutz]

I've had the (mis)fortune of pulling a rifle from the case and, in doing so, spun the exposed target turret enough to move the zero over 10 moa. (Another reason why I like RTZ turrets). I don't see where you mention what the rifle is zeroed at, but a ~10 MOA shift could conceivably move your cross hairs from a 100 yard zero to a 500 yard zero.

p.s. Autocorrect can really make for interesting reading, sometimes.

[Kikn]

KK:

You are right! You sure did 'shit' a 5 round group. Is that your spell checker? He,he.

What was your come up between 200 and 500? Chances are it is around 8 or 9 minutes. If so, nothing is wrong and all you need to do is zero it at farther distances and record your zeros.

LR55

Ooops i thought i had corrected all if those autoincorrects.

My scope has a zero stop and couldnt check the come ups between 200 and 500..i only brought 30 rounds for that gun that was left over from my last shooting session.

[Kikn]

I've had the (mis)fortune of pulling a rifle from the case and, in doing so, spun the exposed target turret enough to move the zero over 10 moa. (Another reason why I like RTZ turrets). I don't see where you mention what the rifle is zeroed at, but a ~10 MOA shift could conceivably move your cross hairs from a 100 yard zero to a 500 yard zero.

p.s. Autocorrect can really make for interesting reading, sometimes.

My gun is or was zeroed at 200 yards previously. It is a vortex viper hd 2 ebr-c.

Yes auto correct causes more problems than its worth. ��

[204 AR]

I recently had a problem like that, it turned out to be a Matrix keymod handguard. Sloppy barrel nut threads. I would have it dialed in, then next time out it's .5 mil high. It did that several times, going up and down. when I thought it was dialed. I even swapped scopes, thinking my vortex had crapped out. When it did the same thing with my Zeiss I started looking at other things. Changed out the Matrix for another ff tube I had laying around and the problem hasn't returned.

[RicosRevenge]

Kikn... since you had to pack up to move from the 100 to the LR; I'm guessing you were at ETTS?

[Texas]

I just had a similar situation with my AR10. Centerline of scope is 3.5 inches above bore. At 100 yds, it shoots 2 inches high, at 200 yards it shoots 7.5 inches high. The only thing I can think of is that my line of sight and trajectory at 100 yds, the line of sight was low and the bullet was still rising tat 100 yards to scope line of sight. Adjusted the scope for 200 yards zero, and everything is good

[Kikn]

Kikn... since you had to pack up to move from the 100 to the LR; I'm guessing you were at ETTS?

LOL that is a great guess And 100% correct. I take it you frequent there as well?

[Kikn]

I recently had a problem like that, it turned out to be a Matrix keymod handguard. Sloppy barrel nut threads. I would have it dialed in, then next time out it's .5 mil high. It did that several times, going up and down. when I thought it was dialed. I even swapped scopes, thinking my vortex had crapped out. When it did the same thing with my Zeiss I started looking at other things. Changed out the Matrix for another ff tube I had laying around and the problem hasn't returned.

I was thinking this as well. But mark at precision put the gun together so I'm about 99.9% sure that's not it. I haven't taken the gun back out yet to investigate. I'm going to try and make time tomorrow for it though.

[Klem]

I cannot think of a AR10 ballistic curve that conforms to that data; 2"/100 and 7.5"/200, unless the gun was not zeroed. As you say, once you zeroed the gun the ballistic curve was then predictable.

[RicosRevenge]

LOL that is a great guess And 100% correct. I take it you frequent there as well?

I've been known to be there once in a while... Ha!