Zero Shift? Tikka/SWFA/UM Rings

[Jimbee]

Good zeros aren’t always a one and done single range trip thing.

This has been my experience.

 

[BBob]

 

[BRTreedogs]

Ok
If you moved your scope forward i would expect zero to shift.
My zero moves after any kind of screw loosening and re torque.

My load seems to not stack quite as well suppressed.
If cold bores high. Then settles down.
I ended up with a barrel cooler and shooting slower to get a cold bore zero.

I also personally shoot with myself in the shade for zeroing. Idk if it applies as much. But shooting west/east with my bow I would notice pretty large left to right shifts. Because the light to the eye and peep or maybe scope tube changes.

Try a much slower, cooler barrel zero check.

 

[B_Reynolds_AK]

This has been my experience.

As mine as well. I zeroed my rifle recently after swapping out an RS1.2 for an NXS for a moose hunt. Zeroed from the bed of my truck on one day, prone with a bipod. The next I went up to the mountains to shoot and decided to check zero one more time from a more normal field prone position. I was .3 mil off to the right. Everything was torqued and locked in place.

 

[Jimbee]

As mine as well. I zeroed my rifle recently after swapping out an RS1.2 for an NXS for a moose hunt. Zeroed from the bed of my truck on one day, prone with a bipod. The next I went up to the mountains to shoot and decided to check zero one more time from a more normal field prone position. I was .3 mil off to the right. Everything was torqued and locked in place.

I try to keep track of my groups with Ballistic X app and it's not unusual for a .1 or .2 mil shift for a ten shot group. If I notice a trend I will slip the turrets. For me, one 10 shot group isn't enough to establish a zero. 3 plus separate groups gives me more confidence.

 

[Miflatlander91]

I’ll absolutely notice a small shift between different positions I need to work on that I’ll sometimes notice a shift just from reloading a mag I’m trying taller rings to hopefully remedy my personal issue


Sent from my iPhone using Tapatalk

 

[wirehead]

Is a zero built based on one set of specific conditions really a zero? I’d propose, as others have mentioned, that a true statistical zero requires all possible impacting variables to be given a reasonable opportunity to have an influence… this includes air temp, mirage, baro pressure, humidity, different setups that change the amount of barrel tip movement between firing and the bullet leaving barrel, trigger torque, case temp, rifle-scope temp differentials… the list is long, I think. It seems to me that at least, to some degree, the observed shift is really observed true variation in bullet trajectory vs point of aim.

One place this is evident is in amateur shooting competitions like my local spring egg shoot. Multiple folks are allowed to shoot the same rifle… a high precision “pre-zeroed” rifle, of course. It isn’t the first shooter that wins but one of the latter shooters that uses the prior shooters’ data for an accurate hold to adjust for change in impact based on that days conditions.

 

[NSI]

Is a zero built based on one set of specific conditions really a zero? I’d propose, as others have mentioned, that a true statistical zero requires all possible impacting variables to be given a reasonable opportunity to have an influence… this includes air temp, mirage, baro pressure, humidity, different setups that change the amount of barrel tip movement between firing and the bullet leaving barrel, trigger torque, case temp, rifle-scope temp differentials… the list is long, I think. It seems to me that at least, to some degree, the observed shift is really observed true variation in bullet trajectory vs point of aim.

One place this is evident is in amateur shooting competitions like my local spring egg shoot. Multiple folks are allowed to shoot the same rifle… a high precision “pre-zeroed” rifle, of course. It isn’t the first shooter that wins but one of the latter shooters that uses the prior shooters’ data for an accurate hold to adjust for change in impact based on that days conditions.

A 100 yard zero at the bottom of Death Valley at 0% humidity is a 100 yard zero at the top of Mount Everest at 100% humidity. Sure, it might be off by.1 mil but it's inside the adjustment range writ large. It is safe to say that you are observing ... other effects.

-J

 

[Formidilosus]

Is a zero built based on one set of specific conditions really a zero?

A 100 zero is a 100 yard zero anywhere on earth.

I’d propose, as others have mentioned, that a true statistical zero requires all possible impacting variables to be given a reasonable opportunity to have an influence… this includes air temp, mirage, baro pressure, humidity, different setups that change the amount of barrel tip movement between firing and the bullet leaving barrel, trigger torque, case temp, rifle-scope temp differentials… the list is long, I think. It seems to me that at least, to some degree, the observed shift is really observed true variation in bullet trajectory vs point of aim.

No. Not at 100 yards.

 

[wirehead]

A 100 zero is a 100 yard zero anywhere on earth.





No. Not at 100 yards.

Funny… I would have thought I was aligned with the Form point of view.

To the technical aspects - you mean, those other factors mentioned tend to not present as significant at 100 yd?

 

[wirehead]

A 100 yard zero at the bottom of Death Valley at 0% humidity is a 100 yard zero at the top of Mount Everest at 100% humidity. Sure, it might be off by.1 mil but it's inside the adjustment range writ large. It is safe to say that you are observing ... other effects.

-J

so the same but not the same…

 

[NSI]

so the same but not the same…

The same, by the measurement techniques available to you.

-J

 

[wirehead]

The same, by the measurement techniques available to you.

-J

Man if you only knew…

Could have been a fun technical discussion. Moving on.

 

[Formidilosus]

Funny… I would have thought I was aligned with the Form point of view.

To the technical aspects - you mean, those other factors mentioned tend to not present as significant at 100 yd?

The difference in 100 yard zero from Death Valley to Mount Everest is approx 1/10th of an inch- so half the diameter of the smallest common bullet. You can’t see that in a group, let alone adjust it out.

 

[TX_Diver]

The difference in 100 yard zero from Death Valley to Mount Everest is approx 1/10th of an inch- so half the diameter of the smallest common bullet. You can’t see that in a group, let alone adjust it out.

As far as my original issue would you think poor original zero (likely due to mirage?) or is there anything to suggest faulty equipment there.

If I overlay groups 2-6 (30 shots I think) they fall within a 2 1/4” circle it looks like.

 

[HighUintas]

My wag has a that it is within shooter error position building. Maybe get a 30 shot zero building position every time with slightly different terrain features. Slightly uphill, slightly downhill, etc

 

[Formidilosus]

As far as my original issue would you think poor original zero (likely due to mirage?) or is there anything to suggest faulty equipment there.

If I overlay groups 2-6 (30 shots I think) they fall within a 2 1/4” circle it looks like.

Probably they would fall into the group formed by 30 single shots with a position break in between each shot.

 

[wirehead]

The difference in 100 yard zero from Death Valley to Mount Everest is approx 1/10th of an inch- so half the diameter of the smallest common bullet. You can’t see that in a group, let alone adjust it out.

Makes sense. Thanks!

 

[ramblinman]

I think a fair number of hunters don’t account for wind on zero at 100

It matters.

Zero on 3mph right wind vs 3mph 270 wind it .1 down and .2 right.

 

[TX_Diver]

As a follow up: I overlaid groups 2-6 (post adjustment) onto a single sheet once I got home. Right at 2 3/16" for 28 shots.

Not as pretty as some peoples groups, but for myself shooting <1k rounds per year I think this is probably reasonable and reflects my level of competency more than a failure of the rifle system?

Open to other thoughts though if anyone still suspects an equipment issue?

I'll do another zero check before my next hunt and then I am switching to factory ammo as I'm not setup to reload at the new house yet. Will shoot a 20 rd group building the position each time prone across my backpack, then do a few drops to check everything again too.