How do you secure your scope base to the receiver?

Discussion in 'Gunsmithing' started by sambo3006, Mar 30, 2008.

  1. sambo3006

    sambo3006 Well-Known Member

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    I just got through watching "How to shoot beyond belief" and they mentioned that they "pin" their scope bases to the receiver, but another method they showed involved using a dremel tool to engrave a shallow X shaped cut into the receiver top between both sets of scope base holes and the same thing on the under side of the scope bases and then putting some epoxy in between them to help keep the base from moving. I am not about grab my rifles and start working with the dremel just based on their opinion, but it did make me think about securing the scope base properly, especially on rifles that have stiff recoil. All I have ever done is apply some loctite to the screws and crank them down tight. Should I be doing more to keep these bases from shifting?
     
  2. Moman

    Moman Well-Known Member

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    Some of the other members will have much more experience with this than I do, I have never heard of it though. One thing I did want to share is I was just reading a little about the new Browning X-Bolt and they are now tapping their receivers with eight holes. They are using one screw in each corner of the bases for a total of four screws per base. I thought this was interesting and they say there will be much less flex in the base.
     

  3. James Jones

    James Jones Well-Known Member

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    I have argued with guys about this to no end , if you hit your scope hard enough to knock the base off the gun the scope is ore than likely gonna be any good , the same goes for up grading from 6-48 to 8-40 screws.

    I personaly bed the base to the reciever with Devcon and only barely tighten the screws till the epoxy cures then they are removed the release agent is cleaned away and they are tightened to the reciever and torqued down , this causes the base to have much more contact with the reciever and when its tightened down to the action will be much more secure than the base with minimal contact , think of it as traction controle.

    I will however retap a reciever to 8-40 if I find the holes in the action to be crooked and this happens alot in factroy gun. On the few bases I've made for rifles I built in a "recoil lug" that fits in the ejection port snugly that will all but eliminate any shifting of the base under any recoil or stress , isit needed , no but it looks cool and functional. I made a base for my personal tactical 308 thatis a titanium 20 moa piccatinny rail , their is 3 , 8-40 screws in the front and two in the rear and the base has two lugs that fit in the ejection cutout that fits snug enough that it had to be lightly tapped in place , you coulden't beat that thing off , is it needed , no ,but it sure looks cool
     
  4. royinidaho

    royinidaho Writers Guild

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    Ditto what James said.

    I am, however, disappointed to learn that the recoil lug on the base isn't needed.:(

    I was about to make a purchase of one of those types. But, hey, it's still way cool;)
     
  5. J E Custom

    J E Custom Well-Known Member

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    Sambo

    Like James I bed the bases if they do not fit perfict,and have never
    had a problem with them.

    I like big bore rifles and pistols with no muzzel breaks and recoil is heavy
    and the only problem I have had was with the windage adjustable bases
    breaking the cap screws that adjust windage. This has been solved with
    duel dove tail rings and bases.

    Some of my rifles exceed 70 ft/lbs of recoil and one of my pistols is just
    under 60 ft/lbs and I have never had a problem with the bases shifting.

    I prefer 8/40 screws but the 6,s will work if the base fits properly.

    Also I use just a touch of lock tight on these screws.

    I would not recomend any file work or extra drilling on a recever.

    J E CUSTOM
     
  6. Boss Hoss

    Boss Hoss Well-Known Member

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    This is the way I do it and the way that it was done by Speedy at SG&Y as we have both found that lock tite fails way too often =

    First use steel 000 steel wool and acetone and rough the contact area of the receiver and then do the same to the contact area of the base.

    Use a cotton ball with acetone to clean any residual off of the receiver contact area and the base or bases. Set aside the base and be careful not to touch the clean areas. Use a little paste wax on the tip of a toothpick to apply into the threaded areas on the receiver. Apply a very thin layer to the screw threads and to the bottom half of the screw head. Set screws on a clean shop towel -- you get the idea.

    Now use JB Weld because it can be heated and removed easier should you want to remove this later on. Mix it and use just a little die if you have it to more closely match the color of the bases and receiver. After mixing on you little piece of cardboard or index card set aside for a few minutes.

    Get your propane torch and heat the contact area of the receiver and the contact area of the bases just enough to bring out any moisture that may be present on the surface. When the bases and receiver have cooled back to less than 100 degrees (this will not take long because you did not heat them up that much) using the toothpick that you used to mix the JB put a small amount on the receiver mating surface and on the base mating surface. Don't worry about it oozing now carefully place the bases lining up the screw holes as closely as possible and gingerly set the base on the receiver---immediately place the screws in the holes and get all of them started a few turns.

    Now that the screws are started give a turn to one and move to the next screw. Repeat process until they are all snug then tighten each one to its final tension. This is important-----DO NOT OVER TIGHTEN. We do not want all of the epoxy to be completely squeezed out.

    Now leave the rifle in the vise and let sit for 5 minutes or so (I use rubber inserts so that the barrel can be clamped in) and get your capful of WD 40, cotton balls and Q-tips. First use dry q tips to remove most of the excess then take a cotton ball and dip a small portion in the WD 40 and very gingerly wipe down the areas you just removed the excess JB. You will notice that it comes of very easy but make sure not to press to hard on the edges where the base and receiver meet we don’t want to disturb that line.

    Use the q tip or the tip of a toothpick with WD 40 on it to clean out any of the epoxy that migrated through the top of the screw holes an also into the openings of any of the screws.

    Now look at the underside of the bases where any excess JB could have migrated into the opening of the receiver or just on top of the receiver for example. Note where a one piece base is used it likes to hide underneath. For this area use the q tip with some WD 40 applied to remove.

    Now go off and have lunch about an hour and use the q tips soaked with WD 40 to smooth (gently) the lines where the base and receiver meet. If you have done everything correctly it should look like one piece of metal!!!

    In 24 hours or 6 using a light to position over the bases to heat them you are ready to mount your scope.


    A final note here make sure to pre fit everything because it will really suck if you find out a base screw is too long and the rifle will not operate!!!
     
    Last edited: Mar 31, 2008