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Two groups same aim point???

B

bradworley

Private
Minuteman
Aug 4, 2022
58
23
Florida
Took my Tikka t3x 6.5 CM varmint out today to break in my new XRS chassis (thanks again @cattleman99 for the great deal!)
I went with my best load-
Hornady 140gr BTHP Match
Lapua SRP
CCI 400
41.5gr H4350
BTO 2.285
Took a few fouler shots and then had a really good 5 shot group when the line went cold.
After about 20 minutes I got back after it with the same load, and used the same aim point. But the next 5 shots grouped to the right???
Still a good group, but it shifted a good .2 inches
What could cause this?
User error? Barrel temp?



PXL_20230130_200731382.jpg
 
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Is this the only time this happened or has it taken place across multiple different groups? I ask because this happens to me and is almost a product of shooter slight position variation or over gripping.

In other words unless its happening repeatedly, id not worry about it. If it has been then check over everything make sure nothing’s loose, making barrel contact etc…
 
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Trigger pull, parallax not adjusted correctly. What was your point of aim?
 
nn8734 said:
Is this the only time this happened or has it taken place across multiple different groups? I ask because this happens to me and is almost a product of shooter slight position variation or over gripping.

In other words unless its happening repeatedly, id not worry about it. If it has been then check over everything make sure nothing’s loose, making barrel contact etc…
Click to expand...
No, I've never had this happen, at least not to this degree.
I guess maybe I'm adjusting to the new chassis? Maybe I'm not getting a consistent sight picture
 
bradworley said:
No, I've never had this happen, at least not to this degree.
I guess maybe I'm adjusting to the new chassis? Maybe I'm not getting a consistent sight picture
Click to expand...
Then I wouldn’t worry about it at all until it becomes a regular occurrence. I can’t tell you how many things I run into when out in the desert shooting including “same POA, two POIs” when zeroing/dot drills etc but I can tell you that 80-90% of the time, I’m the reason not the platform or the ammo.

Are you a new shooter or simply don’t shoot much?

Asking not to patronize or insult, just for context. The more you shoot the more shit you will see and begin to be able to quickly differentiate what issues are shooter-driven and what may be attributable to ammo or platform and how to tell.

The first tell is repeatability. If the same issue keeps happening (esp if it happens with someone else on the gun) the more likely it’s platform or ammo. But wouldn’t worry unless the condition more frequently occurs.
 
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whatsupdoc said:
Try it again but add 2 clicks up elevation so your bullet holes are not changing the point of aim.
Click to expand...
This why I’ve switched over to dot drills for all zero confirmation and grouping drills…gets the shooter to focus on one target at a time vs obsessing over “small groups”. Plus you can clearly see your mean error radius at 100m in a given 5 or 10 shot string

Would recommend @bradworley do the same.
 
First thing I’d check is your parallax. Assuming you know how to correctly use it. Incorrect parallax with different cheek welds can cause this

Next would be a shifting scope base or possibly slid in rings.

That’s just where I’d start looking. Typically you don’t need to bed a chassis with a block in it.

What’s the torque on the chassis? Typically they’re 65 in lbs
 
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bradworley said:
I shoot a lot, but I've only been shooting for precision for about a year.
Makes sense that when weird crap happens it's probably me
Click to expand...
Probably, unless it’s obvious its not and even then it can be hard to spot…In late 2020, i became convinced one of my Schmidt Benders wasnt holding zero. For about three weeks worth of shooting, each time out the zero seemed to shift and it was random. All over the place…I adjusted turrets to rezero like 10 different times, lol. I called up SB and arranged to have it sent back but decided to take it out one last time before packing up the scope.

Started with dry firing drills and as i watched the reticle upon squeezing the trigger i saw it was moving off target in directions ever so slightly with each “shot”. The scope wasn’t moving the reticle, I was. Realized i was changing the grip pressure and sympathetically squeezing the rear bag just enough to cause me to come off target.

Once I figured it out i shot a 6x5 and evey subsequent shot went right on target, no shifts whatsoever. Last time i had to adjust those turrets.

Called SB that monday told them the scope was fine and not in need of repair…

Look it over real carefully and go out again to see if you can duplicate the condition and go from there.
 
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hafejd30 said:
with different cheek welds
Click to expand...
Was in a Frank/Marc clinic and while on the gun in the middle of shooting a group, I lifted my head to look at Marc beside me as I'm hard of hearing and seeing someone talk actually does help.

He yelled at me (well, sort of but I'm the really delicate type! haha) and said "never lift your head.

I asked why....cause I'm like that little annoying kid who always has to ask why.

And he said because I will never get back to the same exact cheek weld and it will change my POI...not by much...but we don't want any, right?

I would speculate that this may be the OP's situation.

Cheers
 
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Baron23 said:
Was in a Frank/Marc clinic and while on the gun in the middle of shooting a group, I lifted my head to look at Marc beside me as I'm hard of hearing and seeing someone talk actually does help.

He yelled at me (well, sort of but I'm the really delicate type! haha) and said "never lift your head.

I asked why....cause I'm like that little annoying kid who always has to ask why.

And he said because I will never get back to the same exact cheek weld and it will change my POI...not by much...but we don't want any, right?

I would speculate that this may be the OP's situation.

Cheers
Click to expand...
Ya it happens 😁

If the parallax is set up correctly it mitigates this fairly well. As far as the crosshairs moving around. However most people don’t understand how to use a parallax and instead don’t use it at all or more commonly just use it as a focus
 
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hafejd30 said:
more commonly just use it as a focus
Click to expand...
Aside from focus...and in fact since the optimum is to get the focal plane of the target and the reticle the same....and doing the little head movement to see that target and reticle stay together, what else is there to it?

If the target and the reticle are on the exact same focal plane, then there can be no parallax error sort of by definition. No?
 
hafejd30 said:
Ya it happens 😁

If the parallax is set up correctly it mitigates this fairly well. As far as the crosshairs moving around. However most people don’t understand how to use a parallax and instead don’t use it at all or more commonly just use it as a focus
Click to expand...
Ya, I set my parallax and don't touch it until I change distance... Which doesn't happen very often.
 
bradworley said:
Ya, I set my parallax and don't touch it until I change distance... Which doesn't happen very often.
Click to expand...
If your reticle and target are both crisp/clear Parallax isn’t your problem. In fact I don’t think you actually have a problem but more shooting will confirm/deny.
 
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Happened to me with my rim fire, one group perfect next one shift. One of the guys said get a perfect cheek weld and sight picture shoot two shots, I did no shift, he took a piece of painters tape and outlined my cheek. As long as I put my cheek on the outline no shift. This was a new chassis I was not used to. Nice groups by the way.
 
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Baron23 said:
Aside from focus...and in fact since the optimum is to get the focal plane of the target and the reticle the same....and doing the little head movement to see that target and reticle stay together, what else is there to it?

If the target and the reticle are on the exact same focal plane, then there can be no parallax error sort of by definition. No?
Click to expand...
If your parallax and diopter are set up correctly is what I guess Im referring to. Where sometimes the clearest picture doesn’t necessarily represent the least parallax. Here’s a link to a thread where it’s discussed. Seems more people run into this with NF ATACR

www.snipershide.com

Rifle Scopes - Parallax vs Image Focus

I saw a thread on here a few days ago with a discussion on parallax vs image focus, so I figured that is a good subject for another video. I tried to explain it the best I could. If it does not make sense, I can give it another shot. http://opticsthoughts.com/?p=2151 ILya
www.snipershide.com www.snipershide.com
 
hafejd30 said:
If your parallax and diopter are set up correctly is what I guess Im referring to. Where sometimes the clearest picture doesn’t necessarily represent the least parallax. Here’s a link to a thread where it’s discussed. Seems more people run into this with NF ATACR

www.snipershide.com

Rifle Scopes - Parallax vs Image Focus

I saw a thread on here a few days ago with a discussion on parallax vs image focus, so I figured that is a good subject for another video. I tried to explain it the best I could. If it does not make sense, I can give it another shot. http://opticsthoughts.com/?p=2151 ILya
www.snipershide.com www.snipershide.com
Click to expand...
Ah, got it. And yes, if your diopter is not in very good focus and your target is, then they will not be on the same plane.

Or, what Koshin addressed as one potential source of error is basically a scope that is not designed and assembled well....best as I can tell because the audio utterly sucks! Well, that and I'm half deaf! LOL

Thanks for the reply.

Cheers.
 
Last edited:
hafejd30 said:
If your parallax and diopter are set up correctly is what I guess Im referring to. Where sometimes the clearest picture doesn’t necessarily represent the least parallax. Here’s a link to a thread where it’s discussed. Seems more people run into this with NF ATACR

www.snipershide.com

Rifle Scopes - Parallax vs Image Focus

I saw a thread on here a few days ago with a discussion on parallax vs image focus, so I figured that is a good subject for another video. I tried to explain it the best I could. If it does not make sense, I can give it another shot. http://opticsthoughts.com/?p=2151 ILya
www.snipershide.com www.snipershide.com
Click to expand...
Ah, I liked this post from the thread you linked and is kind of how I understand it (or misunderstand it, as the case may be).

It is physically impossible for two images to be on the same focal plane, yet one is out of focus and the other is not. That is how the parallax control removes parallax error. It brings one focal plane in line with another. If either the target or the reticle are blurry, then they are—by definition—not on the same plane of focus. That means either the diopter is set incorrectly or the parallax control is set incorrectly or there is a malfunction in the system somewhere.​
 
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All the replies are valid and could mostly all be correct in some way, but what are you trying to do or accomplish with this load? Both groups are roughly .5 moa or less and both inside the same moa sized POA. I think all is well, just your hold may have been a hair different, or a slight breeze came, doesn’t take much to move POI that distance. Next time shoot a 10 round or 20 round group, see if it is the size of what those two groups are if they were overlayed.
 
There are benefits to trying to shoot really small. In the same way, a rifle that shoots really small is a benefit. You discover and learn things that a 3/4 MOA rifle will not likely reveal to you. Like David Tubb stated regarding all those highpower champions coming over from small bore, “there are reasons.”
 
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