Shifting Zero on Long Range Hunting Build

FatboiZ

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So I'm new to long range hunting and this year I have dedicated a rifle build to do just that. I have a Christensen Arms Ridgeline chambered in 7mm Rem Mag. I have Vortex precision match rings mounted to a Talley 20 MOA 1 piece rail. I mounted a Vortex Viper PST Gen II 5-25 x 50 MOA rifle scope. Everything was torqued to spec and the rail was bedded to the action. I have a 5/8' sorbathane cheek riser from Gotta grip on the stock. Im shooting 162 gr Hornady Superformence (SST).

Yesterday I zero'd at 200 yards and got a sub MOA group. I dialed my optic to 3.75 MOA and was hitting a 4 inch steel target at 411 yards,. I was pretty pumped as it validated that I built a good shooting rifle. Well about 15 minutes later I shot at the same target and was hitting about 4 inches low. I then shot at a 200 yard steel target and was hitting around 3 inches low as well. I re-zero'd my rifle and dialed to 3.75 again and began hitting steel at 411 yards again and had no issues for the rest of the day (about 2 hours).

What do you think could cause this? Is there something that I should change or do you think it was from my inconsistencies as a shooter?
Any advice would help.

Thanks
 

cmahoney

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Did you miss right after you dialed back down? I had a vortex viper that wasn’t tracking on a .243 and sent it back. They fixed whatever was wrong with it and I got rid of it.


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FatboiZ

FatboiZ

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So once I missed at 411 yards a couple times I was pretty confused so I dialed back down to 200 and shot at a clean steel target and my shots were 3-4 inches low. So all I can imagine is that my zero had shifted. I even had another more veteran shooter take some shots on the rifle and his shots were low too.
 

PNWGATOR

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If all of your hardware has been degreased, torqued and locked down correctly, and you’ve zeroed with ten round groups, my guess is your scope does not hold zero, track accurately and/or return to zero.
 

madcalfe

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do yourself a favor send the vortex in for warranty and buy a different scope and sell the vortex when you get it back from them. the only vortex that's worth having if your dialing is the Razor gen 2. but i wouldn't be paying that much for a vortex tracking.png
 

TK-421

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This forum loves to hate vortex and is giving some bad advice. The chart above shows that the PST Gen 2 tracks well (over that sample).

There is not nearly enough info to know what’s going on. At this point sending the scope to vortex is a waste of everybody’s time.

Problem as written could easily be shooter error. Could be a problem with the rifle. Could be ammo, scope, mounts, etc.

Isolate the variables and establish your baseline.
 

LookinforDirt

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Right, no discussion of ammo, changes to form, rifle rest used, barrel temperature, new barrel break in, changes in shooting conditions, etc. To easy to blame equipment. Especially with one session of shooting.
 

madcalfe

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This forum loves to hate vortex and is giving some bad advice. The chart above shows that the PST Gen 2 tracks well (over that sample).

There is not nearly enough info to know what’s going on. At this point sending the scope to vortex is a waste of everybody’s time.

Problem as written could easily be shooter error. Could be a problem with the rifle. Could be ammo, scope, mounts, etc.

Isolate the variables and establish your baseline.
out of 9 PST gen 2 only 3 tracked 100% accurate.... thats 33% i dont know how one would call that tracking well....
 

LaHunter

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It's difficult to diagnose your problem for 100% certainty on the internet, but what you describe makes me think you have a scope issue. I have experienced a scope issue similar to what you describe, and you can burn through a lot of ammo and barrel life chasing your tail, with a scope that will not return to zero or track correctly.
 

hereinaz

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I would tear the scope mount apart, degrease, use blue locktite on all screws, reduce by 10 to 5% on torque values cause of wet threads, AND put blue loctite inside the rings. Loctite inside the rings is a fabulous way to keep the scope from slipping. It comes off easy enough. Its far better than rosin.

It doesn't sound like shooter error, he was hitting a small plate at long range then it didn't. It shot low. Another shooter confirmed it.

It could be ammo if he changed type, but inches at 200 yards would be massive for different lots of ammo. I doubt it was ammo, unless he was shooting entirely different brands.

I would bet that the scope slipped in the rings or another screw is loose. It is the most logical and likely. PST 2 don't fail that often.

It could be the scope failed, but that is less likely than installation issues.
 

TK-421

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out of 9 PST gen 2 only 3 tracked 100% accurate.... thats 33% i dont know how one would call that tracking well....
You’re outside of your depth here. Tracking within 2% (ish) is completely serviceable. That level of tracking error is lost in the noise of real world shooter error, real (not internet) velocity SDs, real world BC SDs, ability to accurately measure environmentals, wind etc.

To put it in further context, a 2% error means you can’t even dial the difference until 5 mils. With a 100 yard zero and with the Envinronmentals where I live/shoot, those 162 SSTs will get to ~850 yards with 5 mils.
 

hereinaz

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out of 9 PST gen 2 only 3 tracked 100% accurate.... thats 33% i dont know how one would call that tracking well....
It was tracking errors in the spreadsheet, not losing zero. Tracking errors can be accounted for in software. If it failed to track correctly it would have failed the test. We aren't dealing with a purely tracking error here.

The scope may have held zero, but it slipped in its rings. On four occassions last year at the range I saw guys trying to zero and it was bad hardware, oily threads, and torque.

If it is not ammo or mounting then it is the scope, IMO. Of the three, I think broken scope is least likely.

It very well could be the scope, but sending it back isn't the next step I would take.
 

Tumbleweed

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It is your scope. Any of the other variables the above commenters are mentioning WOULD NOT account for a sudden change of nearly 2 MOA loss of zero. Especially after hearing about your set up and the care you took in mounting your optics. Vortex is famous for inaccurate tracking and failure to hold zero. Send it in and consider selling it after repair, that's what I did years ago.


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Wrench

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Like I told him in the other thread, busted mounts or scope. He described the ammo and situation....pretty classic loose or cracked ring or scope erector saying uncle.

Rifles that shoot decent groups in random locations ain't the rifle.
 

TK-421

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Soooo, nobody even thinks to ask about round counts or see pictures of groups? LOL. Did he zero at 200 with 3-rounds and move on? A couple 5-round groups? More? Did he hit the 4” target at 400 once, twice, 50 times? Was his hit percentage 100%, 30%?

The guy/gal is admittedly new to “long range” and the Internet jumps past the obvious error (him/her) and goes straight into equipment.

As said, could be the scope, but no idea. A bad 200 yard zero and a couple bad shots in the right direction would get some hits at 400. Tons of IFs, MAYBEs, and ASSUMPTIONS, being made to make gear the problem. Consistently hitting 1 MOA targets at 400+ yards is a skill, and a skill that many/most shooters lie to themselves about having.
 

madcalfe

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Soooo, nobody even thinks to ask about round counts or see pictures of groups? LOL. Did he zero at 200 with 3-rounds and move on? A couple 5-round groups? More? Did he hit the 4” target at 400 once, twice, 50 times? Was his hit percentage 100%, 30%?

The guy/gal is admittedly new to “long range” and the Internet jumps past the obvious error (him/her) and goes straight into equipment.

As said, could be the scope, but no idea. A bad 200 yard zero and a couple bad shots in the right direction would get some hits at 400. Tons of IFs, MAYBEs, and ASSUMPTIONS, being made to make gear the problem. Consistently hitting 1 MOA targets at 400+ yards is a skill, and a skill that many/most shooters lie to themselves about having.
i agree with what your saying BUT he already stated sub MOA at 200 yards... then dialed to 400 and was hitting the target" this makes me think he's hit it a couple times by the "i was pumped" of course this is speculation but most people will shoot at something more than once to verify it wasn't a fluke. then after the gun starts to shoot low randomly and also is shooting low at 200 which seems like either A- rings came loose B- scope could be having issues. 400 yards is not a hard shot by any means. A novice can easily do it especially if a gun is set up proper and you have valid dope cards for the rounds your shooting.
 
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FatboiZ

FatboiZ

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Wen I dialed out to 411 yards after my 200 yard zero I was hitting a 4 inch steel target consistently. I put around 6-8 round on the 4 inch target without a miss. I took a break and the next time I shot at the 411 yard target I was missing and was impacting +/- 4 inches low.

I then dialed back to my zero and shot at a 200 yard steel target to make sure I was still zero’d however I was grouping (3 rounds touching) 3 inches low of center.

I then re-zero’d the optic and dialed back out to 411 yards (3.75 MOA) and was hitting the target again.

The barrel is completely and meticulously broken in following Christensen arms carbon fiber barrel break in and the above loss of zero happened within the first 25 round after break in.

Sorry I don’t have photos, I was getting irritated with the rifle so I didn’t take any.
 

madcalfe

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when you took that break in between did you dial your scope back to zero?
if your having good groups but it was 4" low I'm thinking there's something ****** with the elevation turret. loose rings wouldn't or well shouldn't produce good groups IMO
 
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