How important is blue print action

Discussion in 'Gunsmithing' started by remcraz, Apr 7, 2013.

  1. remcraz

    remcraz Well-Known Member

    Sep 26, 2008
    I would like to know just how important truing and lapping the lugs is on a Remington 700. I have a gun that is hitting on one lug while the other side isnt. I am shooting about 1in at 100 yrds. just how much improvement will there be. Im not shooting competition but I would like to get as close to 1/2 in at 100 yrds as I can with a factory gun (300 ultra mag) and hand loads
  2. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004

    Blue printing does not solve other problems that may exist, It just helps to eliminate some problems
    that may later plague your accuracy.

    I will not build a rifle(Any rifle) without checking them because they can be the difference in a 1/2 MOA rifle and a 1/4 MOA rifle. Note: I even check new actions and never fail to find something wrong. (Even custom actions and bolts).

    To have a consistent degree of accuracy rifle to rifle everything must be true to the bore and square.

    Sometimes parts that are not square or centered may cancel out the error and shoot well, But more
    often than not these poor parts compound the error and prevent the rifle from doing its best.

    Lapping a bolt is only good if both recoil lugs are in some kind of contact and can be lapped to 100%
    contact. in your case I would recommend first truing the bolt on a Lathe and then lapping for a perfect fit.

    Also if you have the action trued a precision ground recoil lug should be used.

    Blue printing is only a part of the total accuracy package, but a very important part.

  3. Hired Gun

    Hired Gun Well-Known Member

    Apr 21, 2003
    Is that one lug touching with or without the trigger? With the trigger the top lug should not be touching at all. The bolt is about 4" long. The bolt raceway has .007"-.010" radial clearance. When cocked it is jammed tight to the top hinging the bolt by the bottom lug leaving the upper lug about .002" short of resting on the seat. When the sear is released the brass in the chamber will push the bolt back and both lugs will be engaged. Of the things that affect accuracy in your rifle this is the very last thing to address. Crown, bedding, trigger quality, optics and mounts, rifle fit for consistant cheekweld, barrel quality, appropriate load and lastly action truing is my order of importance.
  4. J E Custom

    J E Custom Well-Known Member

    Jul 29, 2004
    Just to clarify the importance of blue printing(Accurizing) an action these are some of the steps
    when building an accurate rifle.

    First you must start with a great barrel (The rest does not matter if you have a poor one).

    Proper setup of the barrel to assure that it is true to the bore is very important.

    Next=you must cut very good threads that fit the action perfect.(Part of truing the action is to
    chase/true the action threads for the best fit).

    Also very important is the quality of the chamber reamer and how it is set up to cut a perfect chamber. Alignment of the reamer with the bore is of utmost importance before starting the

    Now comes the action. If it is not as perfect as possible all of the previous quality will be negated.
    A trued actions sole purpose is to hold the cartridge in perfect alignment with the bore of the rifle.
    This is why it is very important to have every thing square and concentric with the bore. If it
    doesn't some accuracy will be lost.

    Next and also very important is the head space. Head space can be very precise if the bolt Locking
    lugs are square and have 100% surface engagement , the bolt face must also be square and flat for
    100% contact with the cartridge head to prevent primer pocket and case failure. (Most are dished).
    The amount of Head space varies depending on the use and type of cartridge.

    With all of the steps mentioned before are completed as near perfect you are ready to install as
    good/best trigger as possible.

    Then comes the stock that needs to fit the shooter and needs to be pillar bedded and floated to complement the barreled action.

    So as you can see, accuracy has to be built in and must start at the beginning to be a sub 1/4 MOA or better rifle. If you leave out any of the steps you may go from a sub 1/4 MOA rifle to a 1/2+ MOA

    In the hands of a proficient marksman a precision built rifle can do amazing things without these steps
    it is just a rifle and will never be a shooter in any ones hands.

    You can,t build a mansion on a poor foundation and accurate rifles are the same they must have a
    good barrel, true action and good smithing to perform.