Zero Shift? Tikka/SWFA/UM Rings

[mxgsfmdpx]

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.

Sorry if I missed it. What was the shooting position for these overlaid groups? All shot at 100 yards and from the same position?

 

[TX_Diver]

Sorry if I missed it. What was the shooting position for these overlaid groups? All shot at 100 yards and from the same position?

Prone over my pack with bino harness rear support. The first few posts shows the individual groups and if I rebuilt the position or not

 

[eamyrick]

We call this sniper rifle voodoo for a reason. I’m pretty ocd and have seen what you are dealing with enough to get burnt out on long range shooting. How the sun hits the target, how the sun hits your objective, how tight your shoulder is from doing a heavy workout, plate carrier strap pushing the buttstock, etc.

 

[Formidilosus]

Prone over my pack with bino harness rear support. The first few posts shows the individual groups and if I rebuilt the position or not

This is almost certainly the issue. Very few shooters could do 2 MOA from a pack for 30 rounds.

Start at the start- use a stable rest front and back. A cinder block, real front rest, and real rear bag is cheap and easy to setup, and will show what the gun is doing baseline. Without that, you have no idea if it is you or the rifle.

 

[mxgsfmdpx]

Prone over my pack with bino harness rear support. The first few posts shows the individual groups and if I rebuilt the position or not

Well then that’s better shooting than most despite what the internet will tell you. Everyone on the internet shoots “sub moa all day” even though they don’t ever actually shoot much in real life, let alone from anything other than a bench at a “gun range”. If you really want to chase gnats ass you need a better “position” for the true 100 yard zero.

Zero shifts can still happen even with proven setups like yours. There are no “guarantees” we are simply eliminating as many variables as possible per the Form method as you’ve done.

I finally had an impact shift on one of my .243 Tikkas using UM mounts and scope was SWFA fixed 6. There was no “known” hard drop or knock or anything out of the ordinary. Just used in the field for several thousand rounds and bouncing around in vehicles.

I adjusted the 100 yard zero and the shift has not happened since. I beat on the stock, beat on the scope, it’s been back in the same shooting/riding conditions since and still no shift in over 6 months.

This one was installed with blue loctite instead of paint pen, so maybe that’s the culprit but, again, it hasn’t shifted again since so if it does I’ll pull it apart and see how the loctite held up.

 

[TX_Diver]

This is almost certainly the issue. Very few shooters could do 2 MOA from a pack for 30 rounds.

Start at the start- use a stable rest front and back. A cinder block, real front rest, and real rear bag is cheap and easy to setup, and will show what the gun is doing baseline. Without that, you have no idea if it is you or the rifle.

10-4.

So that’s kind of my question I guess. I can probably shoot a “better group” by staying prone and shooting from a bipod or cinder block with a pint size game changer lite up front and a rear bag, and minimizing how many times I build the position. But if I’m not using that stuff in the field am I not better off getting a zero based on how I’m going to shoot, even if it’s a bit bigger group?

Or do I need (or should I want) that baseline rifle info even if it’s not how I’m shooting in the field?

 

[HighUintas]

10-4.

So that’s kind of my question I guess. I can probably shoot a “better group” by staying prone and shooting from a bipod or cinder block with a pint size game changer lite up front and a rear bag, and minimizing how many times I build the position. But if I’m not using that stuff in the field am I not better off getting a zero based on how I’m going to shoot, even if it’s a bit bigger group?

Or do I need (or should I want) that baseline rifle info even if it’s not how I’m shooting in the field?

I think for determining what load is the best or for identifying a weak link, I would go with sandbags for rest to eliminate variables and figure that out with as few rounds as possible.

But for determining zero for field shooting purposes, I would do it off of what u use in the field and build position every time.

Going even further, maybe find zero by including multiple field positions if you find poi is a bit different for say sitting using sticks vs prone. I haven't done this, but I do find field zero using my pack and rebuilding position. It works well.

 

[Marbles]

I established my zero off a pack with a rear bag (I carry the bag in the field).

The only value I see in shooting from a more stable rest is if you are questioning the rifles capability.

I'm just another nut behind the trigger though, so take what I do with a grain of salt.

 

[Formidilosus]

But if I’m not using that stuff in the field am I not better off getting a zero based on how I’m going to shoot, even if it’s a bit bigger group?

No. The zero is the zero. Zero from the most stable and consistent rest possible, then practice from the pack. Hiding an error by zeroing of the pack if you have a POI shift between the pack and rest, is just stacking errors on errors.

Or do I need (or should I want) that baseline rifle info even if it’s not how I’m shooting in the field?

Yes you want it. If there is a difference in your POI from rest to pack, you need to know that and figure out how to eliminate it. Rifles should not be having a shifting zero between positions.

 

[mxgsfmdpx]

I established my zero off a pack with a rear bag (I carry the bag in the field).

The only value I see in shooting from a more stable rest is if you are questioning the rifles capability.

I'm just another nut behind the trigger though, so take what I do with a grain of salt.

For "checking" a known zero in the field before a hunt this is acceptable. You shouldn't then be correcting out MINOR deviations to a known good 100 yard zero though.

For establishing the baseline/known/solidified 100 yard zero, shooting off of your pack with a rear bag is not ideal.

 

[Marbles]

Yes you want it. If there is a difference in your POI from rest to pack, you need to know that and figure out how to eliminate it. Rifles should not be having a shifting zero between positions.

Other than barrel channel pressure issues, I have always considered a POA change between positions to be shooter error and an indicator of a shooter problem that needs to be fixed. Is that a correct view?

 

[Formidilosus]

Other than barrel channel pressure issues, I have always considered a POA change between positions to be shooter error and an indicator of a shooter problem that needs to be fixed. Is that a correct view?

Yes sir. But, that’s why you don’t zero off of a pack. Zero off of the most stable, most shooter eliminating rest/position possible, then check zero from the pack.

 

[TX_Diver]

Yes sir. But, that’s why you don’t zero off of a pack. Zero off of the most stable, most shooter eliminating rest/position possible, then check zero from the pack.

10-4. Would you do 20 rds from each?

Would you build/break position each time or just for the shooting from a pack to see if there is a difference?

 

[HighUintas]

Good God apparently I suck and I've been doing it wrong for the last few years