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Constant POI Shift

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 09:03
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Optics GrassHopper
Optics GrassHopper


Joined: November/17/2010
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Got quite a problem with my 22-250. For the last few years, this problem has "crept in"and now I can't get rid of it. The rifle WAS a Rem 700 VSSF with a Baush&Laum Elite 4000 scope,6-24X, Leupold STD bases and rings. Hand loaded with Win brass,CCI BR-2 primers, 50 grn Ballistic Tips,36grn Varget.
 
Earlier on this year, the shifting point of impact was so bad I cancelled my groundhogging trip. This rifle used to sit in the safe for days,weeks , months and not get used. I could take it out at any time and smash pop cans at 300-400 yds. Now, the POI shifts from hour to hour.
 
Just a couple of weeks ago I got it back from having a new barrel installed and the action trued. The action has been glass beddded as well as the scope bases, rings have been lapped(years ago)
In a nut shell, I am having the same problem as before all this work has been done . I am now thinking it is a scope problem. I have also changed out bases and rings AND SCOPES(which is a Bushnell 4200 Elite 6-24X, basically the same scope) Is this rifle/scope combo just as bad combination??? I tend to think that it is a long scope on a short action that is causing the problem.
 
I can put the same scope on my 700 BDL 7MM Mag and the POI does not move on that rifle. I am so
frustrated, I gave the rifle a good cleaning and put it away, no use in wasting ammo. HEEEEEELLLLLLPPP
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 09:06
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Optics Retard
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Chief Sackscratch

Joined: December/17/2009
Location: NorthCackalacky
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If you have used different scopes on the gun and are getting the same effect I would say its the gun.  Have you tried commercial ammo just to rule out your handloads? 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 09:22
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Optics Master Extraordinaire
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Joined: November/13/2008
Location: Montana
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Points: 4614
If the bedding is old it may have worked loose and lapping the rings for one scope might not provide a precise fit for the new scope, even if it was the same model. Some part of the scope mounting system may be moving around. However, the most common problem is with the contact between the stock and the barreled action.

Either it is too loose, or the bedding job is stressing the action when the screws are tightened down, or there is contact somewhere along the barrel, which (with exceptions like the Swiss K31) there should never be.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 09:37
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Optics GrassHopper
Optics GrassHopper


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The bedding job was done in April and there is no contact with the barrel. With all the work done, it's practically a different rifle.Remember, it was doing this before all this work, and it's doing it after all this work. I started from the bottom up to eliminate the problem which leaves the scope. I have not tried factory ammo but I will. It's just hard to believe that my more consistant handloads could be the problem. I have tried different seating depths, bullets , powders,etc--all with the same results. Putting factory ammo thru a rifle is like a cumquat in the Garden of Eden
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 09:46
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Superstool

Joined: January/03/2008
Location: Utah
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Lapping rings really should be a last resort.  If you lap to much off the rings, then they are to large and now do not offer the needed grip on the scope and it can move around slightly upon recoil.  Making them pretty much worthless.  So many have jumped on the band wagon of lapping when in many cases it is not even necessary.  But if you have put on other rings and base and did not lap them and are still having the problem, then that is probably not it. 

Just a couple of other thoughts.

Is the barrel free floated?  Are you shooting from a bipod or rest?  When shooting from the bipod or rest is the stock flexing and contacting the barrel?  Many times even though your barrel is free floated, by preloading the bipod or leaning into your rest it can flex the stock enough to touch the barrel which can easily cause POI shifts.

With your new barrel is it a heavy barrel or a sporter type barrel?  The lighter weight the barrel the fewer shots it takes to get it hot enough to change the POI.  A 22-250 is a pretty hot round so if you have a light weight barrel, it may only take 3 to 5 rounds to get the barrel hot enough to start shifting your POI.  A heavy barrel can typically go much more before it becomes a problem.  I am assuming it is a heavier barrel, but just wanted to through that out.

Make sure you are torque your action screws the same every time.  Make sure it is not coming loose.  I am assuming this is an HS precision stock with an aluminum bedding block.  That means you should be torquing those screws to 65 inch lbs.  Check them often, if they are coming loose put some blue lock tight on them.  Probably should do that anyway. 

Also make sure your mounts and rings are torqued evenly as well. 

Hope that helps
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 12:47
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Optics Jedi Knight
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Lord Of The Flies

Joined: March/14/2007
Location: South Africa
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This is a tough one. Shot well before...now it does not etc etc.
So how much money do you want to spend to get it right?
 
Could have been the barrel...so you replaced it. But with which barrel and who did the work? Could still be the barrel. Say you got a lemming barrel or it was poorly chambered. Maybe the threads pitch do not match your old action etc.
 
Many places to start.
 
Explain a bit about "shifting point" Post a target if you can.
 
Do you get 1 shot in one place or two or three and then it shifts etc.
 
The more info the more we can try to help.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 12:59
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Optics Apprentice
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Joined: June/08/2010
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Check your headspace.
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/17/2010 at 23:35
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Optics GrassHopper
Optics GrassHopper


Joined: November/17/2010
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To answer some of the questions that are asked of me:
Head space is minimum
barrel is heavy SS target grade
barrel is free floated -no contact
torqued to 65 in lbs
Weaver bases and rings not bedded or lapped this time-got lucky with a good straight fit that is not binding the scope tube( the Leupold rings and bases were bedded and lapped)
shooting off bench and sand bags-comfortable and solid
shooting in very light winds  2-4 mph about 11 o'clock
the smith that did the work builds sniper rifles for police and military
MacLennan barrel used(Robs barrels hold many records)
 
 Will try to figure out how to post a couple of test targets
Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: November/18/2010 at 00:20
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Optics Jedi Knight
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Lord Of The Flies

Joined: March/14/2007
Location: South Africa
Status: Offline
Points: 5754
Jeez, you have a problem. At this stage I would say it must be the ammo then.
 
Have you tried different powders, bullet weights etc. What rifle twist are you using?
 
With only three post you will have to get some -one to post the targets. Maybe send a PM to one of the guys in USA who have more then 50 posts. They can get the targets up.
 
For now I cannot comment further till I see the targets. But something is way off. Your setup looks good.
Maybe the smithy (Rob) can meet you at a rifle range and see what gives??? 
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