Bedding in front of the recoil lug?

Discussion in 'Gunsmithing' started by j_unzicker, Jan 14, 2013.

  1. j_unzicker

    j_unzicker Well-Known Member

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    Hello Everybody,
    I have a Remington 700 SPS (sporter barrel) in the 7mm mag, laminate stock. I have been reloading and found a load that gave me .45 MOA. I was pretty happy with that for a factory barrel, but I wanted to pillar bed the action so that I didn't deteriorate the stock over time at the action screws.
    After bedding, I am now shooting just over 1 MOA. I taped the bottom, front and sides of the lug and bedded about 2" of the barrel in front of the lug.
    I am pretty sure that before the bed job, the barrel had no contact all the way to the lug.
    Should I start shaving back the bedding in front of the lug and see if my accuracy returns. I am thinking this is probably the problem.
    Any thoughts?
     
  2. squirrelduster

    squirrelduster Well-Known Member

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    If you don't bed the front and bottom of recoil lug why would you bed the barrel at all?
    I would remove the bedding in front of the lug and I bet your groups come back.
    Other question would be what did you use for bedding?
     

  3. j_unzicker

    j_unzicker Well-Known Member

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    I used the deluxe kit from scorehi.com. I think the bedding material is called pro bed 2000. I followed their instructions to tape the sides and bottom and front of the lug for clearance purposes. But they also insrtuct to bed the first 2 inches of the barrel.
    So your advice is to just remove it completely? I guess I could always rebed that area if I needed to.
     
  4. Bullet bumper

    Bullet bumper Well-Known Member

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    You had a factory sporter barreled 7 mm Magnum that shot .45 and you interfeared with it ? I don't usually say this kind of thing but that was real dumb.
    The most likely cause is you have introduced stress in the bedding job.
     
  5. kaseyfied

    kaseyfied Well-Known Member

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    why would you call someone dumb for wanting to make sure their rifle remains accurate over time??.. just becuase a rifle shot .45 without being bedded doesnt mean it will stay that way.. bedding a rifle insures the same accuracy no matter what the weather and temp is.. so maybe your retarded? you should always bed 2 inches or so infront of the recoil lug.. I know smiths that bed the whole barrel channel.. you make sure youdo not have any high spots? that everything was true when you installed it after the bedding compound was applied.. bedding compound shouldnt make too much difference I have used jb weld for christ sakes.. it may be now thats its bedded you have changed the harmonics of the rifle.. and you may need to find a different load for it.. im not a gunsmith but i would make sure you dont have any contact pointsin the bedding proccess..

    kasey
     
  6. Bullet bumper

    Bullet bumper Well-Known Member

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    I appologise for being rude but it may have been better to wait untill it stopped shooting .45 and then try to fix it . Now you have a 1 MOA when you had .45.
    That surely can't be smart . Bedding properly requires skill and experience and it is very easy to screw it up even the pros screw up now and then . Have you not heard the old addage ? If it's not broke don't fix it .
    He need to do research on how to do a stress free bedding job. I hope that may fix it. However don't be too dissapointed if you never see .45 again. I hope you do get it back but also it may have just been a few exceptionaly perfect well matched bullets . I have bedded many more rifles than you sport and I was going to explain the process to him but it seems you know how to do it so you explain how to do a stress free job. I'm all ears.
     
  7. j_unzicker

    j_unzicker Well-Known Member

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    I'm not frustrated with the change in accuracy. For me it is a good opportunity to learn more about how a rifle shoots. I'm not a perfectionist and I'm OK with how it shoots. I just wanting to learn more while dong a fun project.
    Unfortunately I don't have an instrament to measure stress. However, I am pretty sure the bed job is stress free without any high points. The mag box isn't bound and the back of the lug is tight against the bed.
    I shaved back the bedding in front of the lug leaving only about 1/4". After 1/4" the sporter barrel starts to taper. I read somewhere that bedding forward into the taper of the barrel could cause inconsistent harmonics. Anyway...I'll update you on if this makes any difference. If not, I will remove the remaining 1/4" of bed in front of the lug and shoot again.
    Thanks for your thoughts.
     
  8. Bullet bumper

    Bullet bumper Well-Known Member

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    Stress free is also about not bending the action even a few thou while it cures.
    There is a way to tell if it's fairly stress free without equipment but I thought Kaseyfied would explain all that. Im still waiting.
     
  9. j_unzicker

    j_unzicker Well-Known Member

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    Ok...here's the update:
    Shaved off to only 1/4" of bedding in front of the lug - no difference. Removed it all and I shot a 4 shot group at .80. So that is an improvement. However, the bullets were right on top of each other just strung out horizontally. Any thoughts why the gun would shoot so tight virtically (aboit .20) but spread horizontally? My paralax was good. A little gusty today but mostly head wind at about 20 degree angle. I don't have a way to measure torque on the guard screws. Could this be an issue? I am assuming that if the gun can shoot this tight virtically there should be a way to improve the horizontal spread. Am I wrong?
     
  10. FNA3G

    FNA3G Active Member

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    As a general rule of thumb vertical stringing means that the bullet is not leaving the barrel at the same harmonic whip everytime. The fix is usually to go up in charge weights until it works out. Horizontal stringing generally means the bedding job is stressed or something else is wrong with the bedding. There is no good way i know of to tell for sure if it is stressed. The only way to tell if it has something to do with the bedding is either remove it all and have it re done or switch stocks. How many bedding jobs have you done in the past? I know that i sure screwed up the first few i did. It seems simple but there is skill and experience involved.
     
  11. j_unzicker

    j_unzicker Well-Known Member

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    First bed job, but I can't imagine any stress anywhere unless i am not putting enough torque on the action screw and getting tight contact with the bed. I have tightened it snug but not real tight (don't have a torque measurement).
    There is one spot at the end of the tang where the bed looks slightly worn or just a litter darker than the rest of the bedding (after about 50 shots). Could this be a pressure point? Don't know how much the tang would cause a problem.
     
  12. J E Custom

    J E Custom Well-Known Member

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    Bedding a rifle changes the harmonics.

    Bedding the first 1/2"Inch to an Inch is common as long as you remain on straight barrel tenon.

    This helps support the barrel weight and sometimes is nessary for accuracy.

    As I have said many times, Each rifle/barrel is different and sometimes a different approach
    is nessary to get the best accuracy.

    Something you may not have considered is the Load you were using may not be the best load for
    the rifle in it,s bedded state.

    It is not unsual to have to change the load after bedding, altho not very much.

    If the rifle shot .4 before it should shoot better/More consistant now that its bedded.

    J E CUSTOM
     
  13. squirrelduster

    squirrelduster Well-Known Member

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    J E is right. Change the powder charge .3 grains up for 3 rounds and down for 3 rounds and shoot some groups.
    I bet one shoots better than what you have now.
    I wouldn't change the OAL length or primer type. Change one thing at a time, test and record the results. No way to figure out what is wrong if you start changing a bunch of things at once.
    When you shot the .45 group was that the only one or was it a consistent group size?
    One other thing to try is shooting it without the mag box and follower. Takes the stress of that out of the mix. I have had problems with that before.
    Good luck and keep us posted.
     
  14. Broz

    Broz Well-Known Member

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    Did you install pillars? If not playing with action screw torque may be an option too.