When Does an Action Need to Be Re Trued and Lapped

Discussion in 'Gunsmithing' started by CA48, Sep 17, 2010.

  1. CA48

    CA48 Well-Known Member

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    So as the question says when? Is this different for customs actions
    compared to a Rem 700 or a Savage? When my 300 Win Mags barrel
    is done after 3-5,000 rounds do I just screw another one on and get
    to shooting? Or does the action need to be inspected and make
    sure everything is still concentric? Just curious please educate me.
     
  2. J E Custom

    J E Custom Well-Known Member

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    This is just my opinion but I think that all actions factory or custom should be at least
    looked at if you intend to build a shooter.

    J E CUSTOM
     

  3. GNERGY

    GNERGY Guest

    When I rebarreled my Rem 700 in 338 Ultra mag I had Jim at Centershot rifles face the front of the receiver and lap the lugs. I didn't have the threads trued or recut. He installed a thicker recoil lug.
    So far my best group is .625 for 3 shots at 300 yds with the Barnes 225 TTSX.
    Tarey
     
  4. SBruce

    SBruce Well-Known Member

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    Most Re-Barrel jobs that I've heard of include action trueing (to an extent anyway). Unless you're doing it yourself. I think most good smiths will recommend action truing when they put on a new custom barrel.
     
  5. Gene

    Gene Well-Known Member

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    NO, the action does not need to be trued. The accuracy gain by truing a factory action IMO is not worth it. In a custom action, you may want to spend the extra $$$$ The Savage factory bolt head floats anyhow, improving accuracy.


     
  6. J E Custom

    J E Custom Well-Known Member

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    Sorry Gene the bolt face does not "Float" It would be impossible to head space accuratly
    if it did.It can be moved or replaced but must be locked down before head spacing.

    If you want a 200yard rifle only then almost any rifle will work. But if you are into LRH
    every bit of accuracy you can get is important.

    The reason that most custom rifles are much more accurate is that most smiths blue print
    the action for there accuracy requirements.

    It is true that you don't have to blue print .But if you don't you will regret it.


    J E CUSTOM
     
  7. CA48

    CA48 Well-Known Member

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    Thanks for the responses guys but i guess i did not explain myself clearly. I meant after a factory or custom action has ALREADY been trued and lapped when does this process need to be done again. After 5,10, 15,000 rounds, or is the wear so minimal does it ever need to be done?
     
  8. Coyboy

    Coyboy Well-Known Member

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    Once it is done properly, it does not need to be done over if the rifle has been well cared for.

    BUT if the lugs are galled OR the bolt face is eroded, then this would need to be remidied before/during the next rebarrel. I have been sent a few actions that showed some sevier wear. Those that are bad enough may require a new bolt/bolt head, or recutting lugs and abutments. which if bad enough may require repositioning/replacement of the bolt handle for proper primary extraction.

    I have done complete single point "blueprinting" of 90% of the Remington actions that have gone thru my shop. Some customers request a skim cut and lap to save some money. Most of these guns are capable of sub 1/2 moa. I have seen many more complete BP rifles shoot sub 1/4moa right from the get go. I have only seen one skimmed and lapped rifle do 1/4 moa right from the start.

    I would recomend the full BP to most customers looking for the most accuracy.

    If a customer is looking for a 6-7 lb carry rifle for hunting under 300 yards, I would say he could skip the full BP and do a skim cut and lap. He likly wont shoot as well as the rifle.

    But then again some guys are obsessed with the smallest groups possible. If that is you go for the full action recutting. The difference in price petween the skim and lap and full BP is not that much when considering the cost of the completed project.
     
  9. CA48

    CA48 Well-Known Member

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    Thanks for explaining. Its seems to me that it would be pretty pointless
    to skim BP if your going to get any blue printing done at all.
     
  10. mike33

    mike33 Well-Known Member

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    I think Jim See said it very well. IMO if your going to spend a quarter for a skim cut why not just go for the 1/2 dollar and do it right. After all building a custom gun is a luxary if you cant afford it dont do it.
    mike
     
  11. Autorotate

    Autorotate Well-Known Member

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    CA48-Your question means to me an explanation of what truing an action and lapping means, needs to be squared away first to answer your question.

    Truing an action in laymans terms means to make the following three surfaces concentric/parrallel with one common reference/centerline...the bore. When truing an action this usually means-

    1. Action threads are "chased" to ensure when the action is screwed on your barrel, that the centerline of the bolt raceway points straight down your bore.

    2. Action face that contacts the exterior shoulder of the barrel and interior shoulder of the barrel meet with as close as possible 100% contact or "mate up" as the action is "screwed" onto the barrel. Ensures your recoil lug is flat/true and doesn't introduce any stress in the action/barrel junction on non-Wby builds:)

    3. Bolt face is touched to ensure it's surface is exactly perpendicular to the afore mentioned centerline of the bore/action

    Lapping lugs...

    1. A lapping or "mild grinding" compound is placed on the bolt lug/action lug abutements. Rearward pressure is applied to the "trued" bolt face...bolt is cycled against the action lug abutments, until the smith sees 100% contact with all lugs/abutment surfaces, or as close as is possible.

    So by understanding the above procedures, you can see "truing" shouldn't need to be done unless you had introduced a large amount of stress to the rifle (i.e. driving a tractor over it because it doesn't shoot like you want it to:))

    Lapping the lugs could potentially be a "wear" type item, but this would take an excessively high round count with the bolt being placed in some kind of binding/eccentric position over many rounds...or potentially bolt lug/action abutment setback due to overpressure loads that would cause one lug to start picking up the load before others.......both seem to me very specialized situations, not likely encountered.

    During a rebarrel, a smith concerned with the precision capability of the rifle, especially if it was due to accuracy/precision concerns with the rifle in questions, would verify the above surfaces are true/lapped, and then decide it retouching the surfaces was required.

    JE Custom or some of the other super smiths on this site that build lasers....please step up and fix me if I'm off base here.

    Hope that helps.
     
  12. Autorotate

    Autorotate Well-Known Member

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    Why did I just type all that in my post....here's the answer!
     
  13. shortgrass

    shortgrass Well-Known Member

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    Maybe all that typing should be a reminder to all of us to read all the thread before responding. just an observation from afar, no jab intended
     
  14. J E Custom

    J E Custom Well-Known Member

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    It happens to me all of the time because I am such a slow typist that after I read the entire
    post and decide that I may be able to contribute something by the time I finish there are
    several new post that said it very well. OH WELL.

    And autorotate's description was good and gave The reason to blue print in the first place.
    (ACCURACY)

    J E CUSTOM