What's the difference in height over bore between the front & rear receiver rings on a MRC1999/M70.

Testing mounting a scope on an early MRC1999 and I have a difference in the height of the mounted bases, more than I want to shim. The difference between the thickness of the bases is 0.154 ( 0.149 front vs. 0.303 rear) it probably should be less but want to make sure the receiver rings are correct.

I have an early long-action M1999. What exact measurement do you need? I have a sloped base on mine and it is held in place with loc-tite. Attached to the base is a scope, so I can't take anything apart. If I can help, hit me right here...

I'd like to have someone lay a straight edge along the front ring and measure how much lower the rear is than the front.

thanks,

Rob

I'll try that. Gimme a few minutes to drag it out, set up the heavy-duty sawhorses and measure. Don't know if I can get down to .001 inches, but I can try...

HD sawhorses? I can wait til tomorrow. Relax, it's Sunday night.


thanks,

Rob

Here's what I did: I got out my camera and took a big picture of it with an architectural scale next it. I have the .02-inch (1:50) scale next to it. I'll post a small picture here. If you want the original, full-size one, PM me and I'll send it. Mind you, they are big-- something like 2800 x 2100 pix. Take a while to download if your connection is not fast...

I appreciate the effort but I need the vertical difference over the bore, not the length between the bases.
Actually I could just use the differences between the thickness of the Picatinny rail between the front and rear.


thanks,

Rob

Well, there is a way to figure that out. The bolt is .698 to .700 in diameter, and the front ring is 1.470-something. Knowing that, we can subtract back from the picture and figger it out. At least I think I can. Let me look on the MRC website for front ring diameter. There may be info there as to what we need. In the final analysis, you may have to contact MRC and see if they can tell you...

http://montanarifleco.com/Long%20actions.html

The link says the bolt diameter is .698 inches. The front ring is 1.34 inches. From that and the picture, you can add or subtract your way to what you seek. You know the C/L of the bore is .349 inches below the top of the bolt. You know the C/L of the bore is .670 inches below the top of the receiver ring. I calculate the top of th ering is .321 inches above the bolt. The sloped base is 25 moa. I'm thinking measurements can be made along the edge of the base and what you seek determined that way. I'm gonna do some thinkin' on this...

Already have a request into MRC. I would have thought that the difference in ring height was well known.

Real easy way to find out - look up your action on the base height chart from Talley.


http://www.talleymanufacturing...ts&category_recnum=4

The difference is .133

Probably not. The MRC is a clone of the M70, an action that has had millions of scopes put on and taken off for decades all over the world. Bases are machined to fit plus/minus one or two thousandths. It may obtain that someone needs to shim by a red hair or two, but I've never heard of anyone needing to know the difference in height between front and rear base. You might also contact the makers of scope bases for this info. Ken Farrell ( www.kenfarrell.com ) comes to mind. He may be able to help you much quicker than MRC...

Tanker says,

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The difference is .133

Will you look at that! Info faster than the average guy can get to the icebox to get a beer. I love this website...

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HD sawhorses?

The rig weighs eighteen pounds. I call it my "target bitch."

MRC says .120" ± .005.