Burris Rings And An Early 40X

[nickster]

I have a 1965 vintage Rem 40x. I understand that those made before about maybe 1972 had the rear of the action milled about .017" lower than those made after that and current rings should be shimmed maybe.

1. Is that correct?

2. I have Burris Signature Rings with shims, so I could add the .017" back with the shims. How much should I shim? +5moa, +10 moa or +20 moa. Or am I completely off here?

Thanks.

Steve

 

[Turbulent Turtle]

If I understand you correctly, you are saying that the rear of your receiver is 0.17" lower than the front of the receiver. You want to make up the difference with the use of the Burris Signature rings and use the proper combination of inserts (not shims) to accomplish that.

That will work just fine and let me explain the numbers that Burris uses on the inserts. The inserts come in a variety of thicknesses, Burris used to refer to those variations with something like 0 (no variation) +5 (.005" thicker) -10 (.010" thinner), +20 (.020" thicker.)

People were having an issue making sense of of these variations and trying to equate them to something they thought the understood, MOAs. The issue is that in order to come up with a cant or angle value, you have to use trigonometry and you need to know the distance between the centers of the rings. So Burris published a little table that showed the combination of inserts required to achieve a specific cant and for various distances between the center of the rings. That table is available at their website and comes printed with the XTR signature rings, of which I have two pairs. I love those rings.

Now, your situation is different because you are not looking at creating a specific cant, you just want to make up for a manufacturing defect of the receiver. Your questions and the words you use indicate to me that you got confused by the latest plot twist from the infinite wisdom of Burris marketing. They recently stopped refering to the inserts by their thickness variations, but rather they switched the unit of measure from thousands of an inch to MOA, which ONLY makes sense if the distance between the center of your rings is 4.75 inch.

The bozos.

In your case, simply switch back from calling them + or - MOA and instead use the actual real unit or measure: thousands of an inch. So to make up for the manufacturing defect of your rifle, you can use a combination of one + (bottom) and one - (top) .010 in the rear ring with one + (top) and 1 - (bottom) .005" inserts in the front ring or much better yet; use a +20 MOA (aka +.020") on the bottom of the rear ring and a -20MOA (aka -.020") on the top of the rear ring and use the 0s in the front ring.

This way you will make up for the manufacturing defect and have a little bit of a forward cant meaning that your 100 yard zero might be even closer to the scope's mechanical zero.

 

[nickster]

The .017" difference between the old and new 40X/700 is not a defect. They were made that way and Rem changed the back of the receiver for whatever reason about 1972 according to an article in the American Rifleman. I should gave called them inserts instead of shims. You are correct in that the +-10 insert changed the height of the rear ring ~.010" and the +-20 insert changed the rear ring ~.020". I didn,'t know that. I should have realized the answer was much simpler before I asked the question. I ended up using the +20 in the rear. Off to the range tomorrow. Thanks for the help.

 

[KY_Windage]

Trying to predict is an exercise in futility. I always just mount the scope with the Zero inserts front and back, center my windage turret and turn my elevation turret down to about 10 moa above rock-bottom, then shoot the berm and see what changes I need to make in the inserts.

 

[dstoenner]

I have a 1962 Remington 40X with a standard Rem 700 picatiny rail on my 40X. If the rear bridge was .017 lower for my 1962 then the rail would have been tilted and you would have seen light gaps between the rail and the and the rear bridge. I had none. I would have noticed because that is something I check when I mount a rail on a rem 700.

Something is a miss here

David

 

[Turbulent Turtle]

Trying to predict is an exercise in futility. I always just mount the scope with the Zero inserts front and back, center my windage turret and turn my elevation turret down to about 10 moa above rock-bottom, then shoot the berm and see what changes I need to make in the inserts.

My experience has been otherwise. If you take proper measurements and select the proper inserts, you will get very close to your goal and you can easily adjust internally from there. I setup my March-X 10-60X56 HM on my rifle with a 20 MOA canted rail and added an extra 10 MOA of cant with the Burris XTR rings. I set the mechanical zero, added 3 MOA up and then I set up my thermometer target at 100 yards, shot a round aiming at the bottom of the target, I found I needed only a couple MOA of final adjustment.

 

[KY_Windage]

I had a damaged ring (Burris XTR Sig., 1" high, 34mm tube) on a Rem 700, and a spare pair of those same rings, so I decided to replace the damaged on. Well, the finish was slightly different on the unused ones so I swapped out both. Put them in the same spots on the pic. rail, and put the same size inserts in, oriented the same way. Should be the same, right?

Wrong. Tried to shoot a target and missed it. Shot the berm and that revealed I was WAY off. Had to put completely different inserts in.

And this doesn't even get into barrel/action alignment.

If you can measure and predict which inserts will be needed, I'm impressed. Even after doing many dozens of mountings with these rings I don't even try. I have considered getting a bore sighter and using that to predict, but haven't bothered. It doesn't take me that long to take the scope off and swap the needed inserts in.

 

[Infrequent Shooter]

I have a 1962 Remington 40X with a standard Rem 700 picatiny rail on my 40X. If the rear bridge was .017 lower for my 1962 then the rail would have been tilted and you would have seen light gaps between the rail and the and the rear bridge. I had none. I would have noticed because that is something I check when I mount a rail on a rem 700.

Something is a miss here

David

Some PIC rails/mounts are made for 722 and early rem 700s. and others are made for more modern rem 700s. The 40x receivers have the back part of the receiver lower than front. Could be a recent 40x receiver is like the modern Rem 700.

I have two PIC mounts/ one piece that fit my 40x with no space.

 

[D-4297]

When it comes to using the XTR rings ; go to the Burris web-site and do a little research . They have data for correctly installing these rings , and additional information that may not be in the package . Most of the time ; problems with using and setting up the XTR rings comes from lack of information , or not following "THEIR" instructions . I have three sets of these rings on three different rifles , that have three different set-ups . Once "I" learned to follow "THEIR" instructions , "I" had no problems getting them to work . Ya don't go to GM to learn how to adjust the valves on a Hemi , Do ya ?

 

[Ackman]

I have a 1965 vintage Rem 40x. I understand that those made before about maybe 1972 had the rear of the action milled about .017" lower than those made after that and current rings should be shimmed maybe.

1. Is that correct?

2. I have Burris Signature Rings with shims, so I could add the .017" back with the shims. How much should I shim? +5moa, +10 moa or +20 moa. Or am I completely off here?

Thanks.

Steve

If you want to see just use two piece bases and put a straightedge on the front base. See if front and rear are level with each other. I do that anyway with two-pieces bases just to know what's what. Also put a 3' straightedge alongside each base - or 1 piece base - and see if the muzzle is centered between them. And if not, how far off.