VFS Shifting POI

N

NezRongero

Member
Today I arrived on the range to test my new upper and my brother happens to be there as well troubleshooting shifting point of impact on his 30 BR. At least that is the best I could describe.

He had 5 rounds left when I went to see him, so I asked him to shoot the rounds as he would in a match.

1st shot on target 5, wipe out, target 4 wipe out, target 3 down and right, scratch 10, target 2 same spot, gave him 2 L and 3 up, shoot on 2 again, center punch the X. The reason I asked him shoot target 2 again to see if it is position issue.

I have been a high power shooter since I quit stool shooting in the late 80s, I have forgotten how puzzling benchrest shooting for score could be at times, but what I saw had me scratching.

My brother said, he has been fighting the phenomenon for sometime. He showed me some targets that showed wipe out target 5, targets 4 and 3 shifted, then he corrected for 2 and 1 for wipeouts. The thing though, it does not happen all the time. He further said, he had some targets that he did not correct and the shifted POI continued on through target 1.

So, is it a scope issue? Gun handling? Bag issue? Is it rifle precision issue? Or combination of all of the above?
 
I Think....

I think Robert has a March scope. Jackie Schmidt had a problem with his if I remember correctly. Does Robert have another scope? If so change them out and see if the same thing happens. I know this may be difficult since as you state, it doesn't happen all the time. Doesn't keep him from winning matches though. If it's not the scope, it has to be gun handling, condition reading, or in consistent reloading (which is doubtful knowing Robert.)

Also, tell him to check the bedding and make sure it is still firm. I'd try the scope though. If he doesn't have a spare, surely you still have one from your bench rest days.

Good luck,

Virg
 
It's probably optics related.

The only other thing you might check is insure the barrel is torqued property. I have cured more than one POI change by simply tightening the barrel to it's proper tension.

The problem I had with one of my March High Master 48x scopes was the reticle suddenly canted about 20 degrees. I thought the scope had shifted in the rings, but is was the reticle.

March fixed it emmediatly. I sent it to the address as directed, and in less that two weeks it showed back up with the reticle correct and a nice letter from March in Japan.

I have not had any problems since.
 
Curious

You mention that your brother corrected after the POI shifts, which resulted in X hits. What exactly did he do to correct?..... Scope adjustment?......hold for wind? Bag adjustment?...concentration? The reason i ask. Its happened to me, when shooting score.



Glenn
 
Maybe he was shooting in a Left to Right wind and maybe the next time out he was shooting Left to Right Quartering wind, would that not make a difference? just asking.
 
I Shoot....

I shoot in a match with Robert this Sunday. If he doesn't have a spare scope, I'll lend him my T36. That should settle the scope question.


Virg
 
I didn't see that you said what kind of rest your brother was using. Score shooting can be quite different from group in that you are changing the position of the rifle for every shot. The angle in the rest changes and slight differences can easily move you off the dot especially when going from one side to the other. On UBR targets our sighters are in the middle so it a little easier to take a sighter when moving from one side to the other so that one can adjust his hold. It's probably not the optics or they wouldn't return to correct on the next target. Suggest to your brother that he take more sighters. One thing to check would be that the rifle is square to the front of the rest when the match begins. This will help in the adjustments. Also, positioning the rear bag so that the rifle recoils straight back will help some. It's possible not one thing, but all of these combined. It doesn't take much to move you off the dot.

Rick
 
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Chism G said:
You mention that your brother corrected after the POI shifts, which resulted in X hits. What exactly did he do to correct?..... Scope adjustment?......hold for wind? Bag adjustment?...concentration? The reason i ask. Its happened to me, when shooting score.



Glenn
Click to expand...

Glenn,

Scope clicks


nez
 
Greyfox said:
I didn't see that you said what kind of rest your brother was using. Score shooting can be quite different from group in that you are changing the position of the rifle for every shot. The angle in the rest changes and slight differences can easily move you off the dot especially when going from one side to the other. On UBR targets our sighters are in the middle so it a little easier to take a sighter when moving from one side to the other so that one can adjust his hold. It's probably not the optics or they would return to correct on the next target. Suggest to your brother that he take more sighters. One thing to check would be that the rifle is square to the front of the rest when the match begins. This will help in the adjustments. Also, positioning the rear bag so that the rifle recoils straight back will help some. It's possible not one thing, but all of these combined. It doesn't take much to move you off the dot.

Rick
Click to expand...

He is using a SEB front that I put a counter balance on it.
 
virg said:
I shoot in a match with Robert this Sunday. If he doesn't have a spare scope, I'll lend him my T36. That should settle the scope question.


Virg
Click to expand...

He just moved the Lupy from his PPC to the VFS rifle. Have not heard from him as to the results. He is on the range today.
 
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jim1K said:
Did you take the spring out?..... jim
Click to expand...

Sorry, he just asked me to figure out how much weight we can put on the targetside of the rest to keep the top from dropping down from the weight of the rifle. I never messed with the SEB adjustements, he did all that.


Which spring are you talking about, what does it do?
 
NezRongero said:
Sorry, he just asked me to figure out how much weight we can put on the targetside of the rest to keep the top from dropping down from the weight of the rifle. I never messed with the SEB adjustements, he did all that.


Which spring are you talking about, what does it do?
Click to expand...

There is a leaf spring in the earlier SEB rests. Not sure if they are in the newer ones. Mike Ratigan recommends that they be removed. My MAX works much better without it when using the counterweight.

Rick
 
jackie schmidt said:
It's probably optics related.

The only other thing you might check is insure the barrel is torqued property. I have cured more than one POI change by simply tightening the barrel to it's proper tension.

The problem I had with one of my March High Master 48x scopes was the reticle suddenly canted about 20 degrees. I thought the scope had shifted in the rings, but is was the reticle.

March fixed it emmediatly. I sent it to the address as directed, and in less that two weeks it showed back up with the reticle correct and a nice letter from March in Japan.

I have not had any problems since.
Click to expand...


Jackie,

Do you have any rough estimate as how much toque is needed if I were to use a torque wrench on a rear entry wrench?

Nez
 
Greyfox said:
There is a leaf spring in the earlier SEB rests. Not sure if they are in the newer ones. Mike Ratigan recommends that they be removed. My MAX works much better without it when using the counterweight.

Rick
Click to expand...

Rick,

Thank you, will pass information to my brother.

nez
 
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Years ago

I had a 1-17 lilja chambered in 30 BR by a competent gunsmith. It was going on a Panda. I bought the action used and someone had the bolt face opened to accommodate the BR cartridge and in so doing increased the headspace by about .008".

The smith caught that when he measured the tennon length. I put the barrel on and torqued it and it seemed to shoot fine. However mid way through a match the gun would start opening up, very frustrating. I finally put the rifle in my vice and when I put the action wrench in the action just fell off the barrel. Hum?

I sent it to Gary Long and he diagnosed the problem as the last bit of unthreaded tennon before the shoulder. The threading tool had come out a bit too soon and that unthreaded part was not allowing the barrel to really lock up against the action face. It sure looked like it did but it wasn't. Once corrected that barrel shot beautifully. Just a thought.
 
Looks like the POI shift might be pointing to the scope.

He mounted the Lupy and shot in the local match today. Though he did not do well at all, he did not see the obvious POI shift.

I believe he will try to send the March to Deon
 
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NezRongero said:
Looks like the POI shift might be pointing to the scope.

He mounted the Lupy and shot in the local match today. Though he did not do well ar all, he did not see the obvious POI shift.

I believe he will try to send the March rio Deon
Click to expand...

A simple check is to try a different scope. Maybe he's already tried. If so, I apologize.
 
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