removing and reinstalling stock

Discussion in 'Gunsmithing' started by jmason, Jul 20, 2008.

  1. jmason

    jmason Well-Known Member

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    When removing your gun from the stock and reinstalling it, how is it possible to need to rezero te gun. I read somewhere that guns would lose their zero after this sort of thing. If you don't remove the scope, mounts, etc. how can the relative accuracy be effected? When i say relative I mean like moving an inch. Maybe I need a picture?
     
  2. ss7mm

    ss7mm Writers Guild

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    It may not be necessary to re-zero your gun but you absolutely should check it if you're going to be doing any long range shooting.:rolleyes:

    Some will move and some won't. I personally wouldn't take a chance. A factory gun in a wood stock would be a major concern. A full blown custom that was built right would be a smaller concern to me but, if it comes out of the stock, if a scope comes off etc. etc., it gets re-checked. I don't want any surprises. If minute of garbage can lid is o.k. then don't worry about it. If you want half moa or better, at poa, at loooong range then what do you think should be done?;)
     

  3. jmason

    jmason Well-Known Member

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    I recheck everything to a fault. It takes me more time to perform some tasks than most but I can't deal with any doubt that my stuff is 100%. It also scares off those "shooting gremlins"! My problem is understanding what the heck could cause your zero to change by taking the gun out of the stock and putting it back in. Mind you, I'm not having a problem. I'm just trying to understand something. I also mean that when removing and reinstalling the gun that the scope and mounts are untouched. I don't see what could cause anything to change in that situation. I totally agree with checking. I'm just at a loss as to what could happen. I read others talking about it but can't find the thread. If I did find it I'm not sure the answer would be there either.
     
  4. ss7mm

    ss7mm Writers Guild

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    I guess one way to think would be a worse case scenario with a factory gun and a wood stock with no pillars or bedding. It would be possible for the gun to be placed in the stock in one position, removed and because of the sloppy fit/bedding it might then be replaced and tightened down in a slightly different position. This could and would put far different stresses and pressure on the barreled action and stock. This would be one way zero could change.

    With a bedded rifle what would happen if the recoil lug was bedded tight on the bottom and for whatever reason, something got shaved off the bedding or something got into the bottom of the lug recess. Again, the possibility of different stresses although probably not as much as the above mentioned wooden stock scenario.

    I have a gun that Kirby built using an A5 stock bedded and pillared and all done right. I can take the barreled action out and replace it and poi at 300 yards won't change 1 click. My buddy has a factory 700 in 308 with the factory wood stock that was bedded by someone that left a little to be desired as far as precise fit goes. This particular gun was bedded in the recoil lug/front ring area of the action only. Pull the barreled action out of that wood stock and replace it and it will change poi at 100 yards by 1" or more. There's no way you could get the pressures and forces the same each time with that gun because the action can rock in the stock because it's only bedded with about 1/4 of what might be considered a propper bedding job.

    Have two people remove and replace a barreled action with one doing it haphazardly and one using a good torque wrench and the results will probably be different. I've heard people recommend that you place a barreled action into the stock with action screws only slightly tight and bump the butt on the floor to make sure the barreled action is seated firmly to the rear in the stock. In some cases this will make a difference.

    You could round up 100 normal, one box a year shooters, and have them shoot, remove and replace and shoot again and they may get a different poi every time. Take the average guy on here with a precision long range rig and have him do the same and the results will be far different. Any physical measurement, dimension or property of a rifle that could possibly change when removing and replacing a barreled action has the potential to change poi. If the guns is built right and we do our part with the mechanics of the removal and replacement and the chance of much variation in poi will be eliminated.
     
  5. Joel Russo

    Joel Russo Official LRH Sponsor

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    Well put ss7mm.
     
  6. jmason

    jmason Well-Known Member

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    Thanks, I never gave thought to stress areas on the gun changing when you do that.
     
  7. NesikaChad

    NesikaChad Well-Known Member

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    Bedding

    Done properly, a rifle should not experience a zero shift when the barreled action is removed/installed in the stock.

    How can I possibly say this? It's cause 1000 yard shooters quite often have to fly/drive long distances to matches (all over the world) and it's not realistic to case a rifle thats in excess of 50 inches long from recoil pad to muzzle crown.

    So, the the sights come off and the barreled action is pulled from the stock. It only takes a couple sighters to get back on track once all this is put back together. The zeros recorded in data logs and notebooks very seldom change and when they do, it's typically from an atmospheric change in conditions. A torque wrench is an essential piece of gear here. Even more critical in smallbore shooting.

    Just an FYI.
     
  8. jmason

    jmason Well-Known Member

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    Chad,

    Thanks for the FYI. My question was more geared to an unbedded sporter type rifle. Unfortunatly the closest I'll ever be to a gun matching your description (or flying around with it) will be in my dreams....

    :rolleyes:dreaming:rolleyes:dreaming
     
  9. NesikaChad

    NesikaChad Well-Known Member

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    "stock" stocks. . .

    Thanks for the kind words.

    Ya' know, there are a great many hard hitting bolt guns out there that are not bedded. A great many. If your stock is synthetic, or if its wood that has been sealed up well, then not much should change either.

    Again, here is where the torque wrench is your friend.

    Maybe just do a little experiment over the summer. Go the range and shoot as you normally would.

    Before leaving, clean the gun.

    Next range session, fire 5-10 rounds into the berm to foul the bore. This is to eliminate fliers occurring from shooting on a clean barrel. Then pull the barreled action from the stock and reassemble. (torque wrench the guard screws, no more than 40 inch lbs)

    See if there is a zero shift on the gun. Pay attention obviously to the first round fired and then the following ones. Also, pay attention to the weather.

    Do this over the course of the summer or hell, even over a solid day of shooting, and save your test targets. Might be interesting to see what comes of it.

    you may experience a flier or two and then the rifle settles right back down again. This is not an alarming thing. The indicator of a stock/action-barrel fit problem is when there are significant changes in the gun's no wind zero. A group that changes from center mass to 3 o clock for instance, only to change again next time you pull the action from the stock.


    See what you find, good luck.