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Scope Sliding Under Recoil - Solution?

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Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/11/2007 at 23:56
Joe Williams View Drop Down
Optics GrassHopper
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Joined: July/14/2007
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Quick Question... How do I stop my scope from sliding in the rings under recoil?  You can assume I 1. tightened everything according to spec and 2. degreased the scope tube and rings first.

 

Specifics.  TPS TSR 30mm Low Rings (Alloy).  Meopta Meostar 4x16 scope.  LaRue 5/8" riser QD picatinny rail, DPMS LR-308 w/ SS 24" bull barrel.  All new.

 

I was having accuracy problems all day.  And, I was fighting a tight chamber that every 15 or so rounds resulted in a FTE where the extractor would rip the rim of the case (yes, I polished the chamber after it did this and it still does it).

 

I could accept the FTE for the moment if I'd been shooting nice groups but all kinds of ammo were producing 2.5" groups at 100.  I remember one specific group of 5 shots of Fed Match 168gr that all strung vertically (Now I know why).

 

This evening I was rechecking all the screws to confirm they were tight and realized the scope had moved, sliding back about 1/2" in the rings.  And all the screws were still tight..

 

So, what do I do?  Shim the rings with scotch tape?

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/12/2007 at 00:26
www.technika.nu View Drop Down
Optics Journeyman
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Joined: August/02/2005
Location: Sweden
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Hi

 

Buy Brownells Rosin in but betwen scopes and rings( it a powder)

It's exceptionally effective and the day you want to sell the scope you can easaly wash it off the scope with some alcohol.

I do always puts in rosin on all scopemounts.

 

Regards Technika

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/12/2007 at 09:36
cheaptrick View Drop Down
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I'm sorry your having such a time.

 

I'm going to forward this post to TPS Phil who hangs out here.

Maybe he can shed some light on this dilemma. I think either your scope tube is out of spec, or the rings are.

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/12/2007 at 09:54
Dale Clifford View Drop Down
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Joined: July/04/2004
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its the gun sliding forward, but inertia is pretty boring stuff-- put a light coat of sizing lube on the rounds you are testing and see if they work, then go back, to non coated, if they still seize, send the gun back as your looking at a case head seperation or more depending on how bad. another test is try reloads with about a 5gr. reduction in powder, if they still stick, call dpms. from the group size I suspect a neck problem, if they still seize when lubbed.

rosin, or double sided tape as suggested, or epoxy (resin), (don't forget to coat with releasing agent)

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/12/2007 at 12:09
TPS_Phil View Drop Down
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Sliding isn't good,

 

I have to ask, because if the installation isn't right bad things happen?

 

http://www.tacticalprecision.com/pdf/TPS_Instruction_Sheet_P DF.pdf

 

Did you tighten with a torque wrench (15 inch pds) or by hand?

 

Thumb

Pointer Finger at End.   When the wrench starts to flex it is real close to 15 inch pds.

 

Phil

 

 

Post Options Post Options   Thanks (0) Thanks(0)     Back to Top Direct Link To This Post Posted: August/12/2007 at 21:03
Joe Williams View Drop Down
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Joined: July/14/2007
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Phil,

 

Thank you for checking in and asking.

 

This is my second set of TPS rings and I like them a great deal based on build quality and price.  My other set holds a Millett scope on my CQB AR in .223.

 

I hand tightened the screws using the supplied wrench.  I tightened them as tight as I could.  When I removed the screws to reposition the scope this morning I had to use a torx bit and 1/4 ratchet wrench.  Each one was tight and 'squealed' as it let loose. 

 

I measured the scope tube and it measures 29.93mm to 29.95mm, also the finish on the Meopta tube is extremely slippery.

 

I degreased again and I used some rosin (from a baseball batter's rosin bag) on each side of the rings and retightened the scope.  I put about 140 rounds through the gun today.  I just confirmed my measurements, the scope moved 1/16" of an inch, much less than yesterday but it still moved.

 

Any other suggestions?

 

I wish I could blame accuracy grumbles on the scope movement but 1/16" move divided by 140 rounds means it didn't move much between shots.   And my FTE issues complained of above can only be blamed on the barrel manufacturer.   Say.. anyone want to buy a nearly new .308 AR?    Perhaps I'm more of a 'Bolt Action' guy..

 

Thanks,

 

JW in Houston.



Edited by Joe Williams
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