FTP 900 stock shim

Discussion in 'General Airgun Chat' started by Grenade, Feb 23, 2015.

  1. Grenade

    Grenade New Member

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    Hi Guys,

    What is the purpose of the stock shim?

    When I took a close look at my FTP 900. I noticed a gap between the action and the stock. By removing the shim, The stock to action fit is a lot better.

    Is there any disadvantage to removing this shim?

    Junaid
     
  2. suds

    suds Senior member

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    It was fitted to lift the action to cure zero shift
     
  3. peter b

    peter b Member

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    Stock shim

    Hi Junaid,
    Keeps stock a little clear of the wood which can move in climate changes which could result in point of impact shift.
    Regards Peter
     
  4. vinny

    vinny WHFTA 2015 World Champion

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    Hiya,
    my stock action clearance was a bit excessive with the shim so I removed it, I did have to slightly enlarge the holes in the side of the stock tho much better fit , no poi change either,
     
  5. Tench

    Tench WHFTA World Champion 2016.

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    Wood moves a lot with temp and humidity, remember when your wooden front door was jammed shut in the winter and loose in summer? If your action is pressed hard onto the wood it may not hold zero from one season to the next or maybe not even from one weather front to the next, fitted correctly it should hold zero for years.
    if you have ever had a Ginb stock with the alloy inserts in, did you notice that sometimes they are recessed and sometimes standing proud due to the wood expanding and contracting?
     
  6. Grenade

    Grenade New Member

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    The shim is a metal plate, about 1mm thick. If the stock swells, the shims going to move with it ...won't it? It would be better to glassbed the action to minimize movement.

    I have a beautifully figured stock on my Sako Classic 308. The grain ran at an angle trough the fore end. You just had to show it a damp cloth and the fore end would warp. One side of the barrel channel pressing on the barrel it's self. I cured the problem by inletting a small piece of aluminium I-beam and glass bedding it in place. Now the rifle's POI doesn't **** with any sort of weather change.

    I also have a Ruger gunsite scout rifle in .308. Stainless with a laminated stock, similar in material to the FTP stock. I coated the inletting with marine spar varnish. Its been out in the rain, snow, hot weather and out in the cold to -5C with no sift in POI.

    I'm going to use the spar varnish on the inletting of the FTP stock. I'll keep an eye on POI shift in different weather conditions and let you know how I make out.

    If I'm missing something please let me know.

    By the way, I didn't have to enlarge any of the holes for the mounting bolts in the stock.

    Junaid
     
  7. Tench

    Tench WHFTA World Champion 2016.

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    When I fit an action I would shim it to be touching in the stock just infront and behind the fixing screw and no where else. especially along the length of the air tube. if the tube touches at the front and the action at the back the bolt so many rifles have going up through the stock into the action can bow the action as it tightens. This can often be seen by the gap between the end of the barrel and air res closing slightly as the screw is tightened, I have seen this many times even without the bolt feeling tight. Actions with a front barrel support will still shift zero if bowed in the stock. This bowing will vary as the wood expands and contracts. Shim it so you can slip a sheet of paper between the air tube and stock along its whole length when the stock is tight and you will eliminate the woods influence on the action.
     
  8. Grenade

    Grenade New Member

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    Thanks Tench,

    The FTP has a rail extending out from the action. Attached to the rail is the cylinder and barrel support (sort of like a eight)

    I had asked about glass bedding the action on pcps on another forum. I was told that it didn't make a difference. I think you're on the right track. What you described sounds like free floating the barrel on rimfire and centerfire rifles.

    I'll do this to my S510 and Regal.

    Tanks again for your advice.

    Junaid.
     

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