Mosin nagant 1891/30 drill and tape for ATI scope mount

Discussion in 'Gunsmithing and Repairs' started by mookiie, Apr 3, 2016.

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  1. mookiie

    mookiie Member

    Sep 16, 2010
    Can anyone offer advice I am looking to drill and tape a ATI scope mount to a Mosin Nagant 1891/30? How deep do you drill the holes? I have not yet gotten the kit yet so I am in the information gathering phase.
  2. farmerboy78

    farmerboy78 Member

    Jan 19, 2010
    I first run a tape measure through the action and touch the chamber end of the barrel, then measure to the rear side of the front section of the receiver where the bolt rubs. I then mark on top of the receiver where the barrel starts in the receiver, and then find center of the receiver. Then line the receiver up to where you will miss the chamber with the screws. Once it's lined up, clamp the mount to the action. Once clamped, I like to find a drill bit that is the same size as the hole going all the way through the mount, and begin to drill slightly giving you each of your centers. Once centers are found, use the drill bit that is sized for the tap and drill completely through the receiver and tap each hole while using lube on the tap. Then, clean out any burrs sticking down into the bolt raceway. Securely attach the mount withe the screws, and then look through the bolt raceway and see how much the screws stick down and slowly grind each screw to length. Once the correct length is found, use blue thread locker and attach the mount and your done.
    Last edited: Apr 3, 2016
  3. LAGS

    LAGS Member

    Nov 12, 2013
    Mesa Arizona
    If you are only using the two screws that come with the scope base, then I suggest that after the receiver is drilled and tapped, you glass bed the bottom side of the scope base to fit the receiver with JB Weld.
    Then even with Locktite, the mount has less chance to shake loose.
    Remember, that mount is made to fit both the Round and Hex receivers.
    If the bottom of the base is Molded to fit YOUR receiver, then less chance it has to move side to side and loosen the screws.
  4. WardenWolf

    WardenWolf member

    Nov 11, 2008
    Northern Virginia
    If you are also planning on doing the bolt handle, there's relatively inexpensive proper conversions such as this one:


    That way you won't wind up with a wobbly bolt-on handle.
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