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Thread: Why is my scope out of zero?

  1. #1
    Sharp Shooter

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    Default Why is my scope out of zero?

    Hi,

    May be some more experienced guys can explain this to me - after the last shoot and rain in Alberton, I took my action together with the scope out of the stock in order to dry it. I put it back on and then my POI at 30m (zero range) shifted about 40mm up. Why is that? I didn't touch the scope at all. Adrian also had the same change of zero with his rifle. He was explaining the zero shift is due to different tightening of the stock screws to the action. Is that the only reason for such change?
    Also, if my screws get loose while shooting and I re-tighten them again, is my zero going to change again?
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  2. #2
    Inactive Member

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    Hi mate, I'm sure someone better qualified can explain it better than me but it is often the case if you remove the action from the stock you will need to re-zero.
    Tiny differences in the way it seats can translate into bigger differences down range.
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  3. #3
    Protea Benchrest (Air) Team '08/'10/'11/'13/'15

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    I know that in rimfire rifles you must torque the bolts on competition rifles as there is a change in harmonics and your poi will change.
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  4. #4
    Marksman
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    on what rifle Swordfish?
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  5. #5
    Sharp Shooter
    SAFTAA FT Colours '10

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    I am not the a great shot but take my 400 out of it's action regulary and have not had the poi change you are refring to. Maybe I just have the torque wrench hand
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  6. #6
    Marksman
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    It can be quite common for the POI to change on an S400 when torqueing the stock screw differently due to the way the barrel is mounted inside the collar attached to the cylinder.

    It is very dependent on the amount of pressure the front of the stock pushes up against the cylinder...hence my preference for free floated barrels...
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  7. #7
    Sharp Shooter

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    Quote Originally Posted by guido View Post
    on what rifle Swordfish?
    HW97K
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  8. #8
    Protea FT Team '08

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    Quote Originally Posted by swordfish View Post
    Hi,

    May be some more experienced guys can explain this to me - after the last shoot and rain in Alberton, I took my action together with the scope out of the stock in order to dry it. I put it back on and then my POI at 30m (zero range) shifted about 40mm up. Why is that? I didn't touch the scope at all. Adrian also had the same change of zero with his rifle. He was explaining the zero shift is due to different tightening of the stock screws to the action. Is that the only reason for such change?
    Also, if my screws get loose while shooting and I re-tighten them again, is my zero going to change again?
    Swordfish I am no springer pro.I however did hear some of the springer pro's at worlds complain about the rain.They were saying with each loading of the gun you suck water into the chamber and that would be the end of a nice day shooting.

    I guess the water interacts with the lube in the chamber ?
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  9. #9
    Sharp Shooter

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    Hmmm, I think I have to play with this one when I have a bit of time. I'll zero the scope, then un-tighten the stock screws a bit and see what happens. Then zero again, remove the action and put it straight back on...
    Will let you know of the results.
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  10. #10
    Sharp Shooter

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    Glass bed the action?

    Just a thought, dunno if it'll help on a springer but did it on my S400 and no shift when removing and replacing action.
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  11. #11
    Sharp Shooter

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    Quote Originally Posted by Mac View Post
    Glass bed the action?
    What is that and how do you do it?
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  12. #12
    Sharp Shooter

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    The centrefire, and rimfire, blokes do it.

    Basically the idea for them is use a glassfibre or epoxy agent to bed the action of the rifle into the stock and leave the barrel free floating so if the wood stock expands it dosn't touch the barrel and ruin the harmonics of the barrel.

    This involves drilling holes into the stock for the epoxy to bond to. A release agent is put onto all metal parts of the action that will come into contact with the glass. the glass is mixed, put into the stock, the action inserted and bolted down,everything left to cure then hopefully the action can be undone and removed and the glass has formed a perfect bed that wont be affected by stock swelling or shrinkage.

    Scary stuff the first time you do it!

    Think there's a kit you can get to do it but I used one of the epidermix epoxies.

    Piet Skiet would be more qualified to explain it, he talked me through it. Think he did it to his Dommie, and probably most of his centrefires.

    Like I say, I don't know if it'll help on a springer, but pretty sure it won't do any harm.
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