Indexing picatinny rail to rifle receiver

[strangefire]

Hi everyone
      I have a older rifle that has never been drilled and taped for a scope so what I would like to do is mount a picatinny rail on it and before I start drilling into the receiver/barrel I would like to know how to index the rail so it's straight inline with the barrel. Thanks for any advice you could give me!!

[gunnut69]

I've seen folks clamp or glue the bases to a receiver with said receiver leveled in the vice. Leveling the base, left to right from behind, gives top dead center of form. With the base secured to the action a transfer punch can be used to created a dimple at the center of the mounting hole. Of course the drill press or mill must also have the action leveled and in both directions before the holes can be drilled. A jig uses hardened busgings to assure the bit doesn't walk and taps enter the receiver perpendicular to its axis.. you have to accomplish this with the setup and a good drillpress. I strongly advise the use of center drills to start the holes squarely. Or you could just take it to the local smith..

[strangefire]

Thanks gunnut
        Drilling shouldn't be a problem since I have a mill, but my biggest concern was getting the scope rail straight the first time. How about after I clamp the rail to the receiver I install the new scope and use a bore sight tool to check alignment? Also what type of levels are the best to use getting the receiver level? or once I clamp the receiver in the mill vice I could use dial indicators to ck level/true

[Nobade]

I do it with a good, proven collimator, a pair of Weaver base bottoms and a non adjustable try scope. If it looks like things will line up I will go ahead and fit the base. Then when you screw it down and find out it doesn't line up anymore you can epoxy bed the base to the receiver with the screws barely tightened and make sure it'll work.

Most time if it's a good barrel you can hold the barrel in V blocks, find the edge, and move in to their center. That should put you on center of the receiver, but of course double and triple check everything before you punch the first hole. Once the first screw is in, put the base on and check to make sure it bore sights. Then when it's perfect move over and do another hole. If everything is good the base should be straight now, and the rest of the holes are easy. Just take your time and be careful!

BTW, what kind of rifle are you fitting a rail to that isn't drilled already? That's kind of unusual.