Rem 700 and Clone Scope Rail screw spacing

[carlsbad]

What do you guys use for screw spacing. There is a lot of minor inconsistency between manufacturers of rails. Here is what I can come up with:

All dimensions center to center except frist one which is edge to center.

Front screw is consistently .190 off the front edge of the receiver.

Spacing of front 2 screws is usually listed as .860. Badger uses .862.

Spacing of rear 2 screws varies more. Ken Farrell uses .600. Badger uses .605. Others in between. One random internet guy used .607.

SA spacing between front and rear:

Ken Farrell and Badger both use 3.630. One sketch by unknown artist on the internet (comes up in every search) is dead wrong at 3.65. Good example of bad info on the internet.

LA spacing between front and rear:

Ken Farrell uses 4.480. Badger uses 4.485.

I found a few other references that didn't conflict. Didn't record them.

Nightforce doesn't publish any numbers or I would probably use them since I use more NF scope rails than anything else.

--Jerry

 

[Dusty Stevens]

Cant you just measure the nightforce rails you have? And if you really think about it .003 in one of your examples is actually very fine. Put .003 in your calipers and hold them up to the light to see the gap. Scope bases, especially one piece jobs, dont have to be perfect. Im sure the action has a tolerance of .010 total or maybe more

 

[carlsbad]

Oh I agree. I've never had one that didn't fit. I'm just deciding what numbers to put in my permanent files.

Yes, I will measure a NF Next time I'm out on the mill.

As a certified obsessive compulsive, I really like to have screws centered in holes...

 

[rammac]

Actually, from a machinist's point of view, hole locations are critical and need to be within a few thousandths of an inch in order for the screw to fit properly. You have to remember that you have tolerances for the hole, the screw, the threads, and the location of the holes, all those tolerances stack up pretty quickly and in order to keep them in the proper relationship to each other the actual location of a screw hole it usually required to be very accurate, the smaller the screw the tighter the location tolerance. For a standard fit using a number 6 or number 8 screw you need to locate the hole to within plus or minus .0035", a close fit is about plus or minus .0025".

 

[GenePoole]

A decent one-piece scope base will have a recoil lug of sorts and slightly slotted holes to ensure that the lug makes solid contact with the ejection port. I prefer NightForce rails as well. I've always used the Badger specs though. No good reason, but since they go the extra decimal point, they must be right, right? Anyway, the Remington hole spacing is very inconsistent among the actions I've measured. My technique is to line up the action by the bolt raceway with a mandrel and bushings (the de-facto reference datum for most smiths), center the Y off the mandrel, then find the actual X dimensions of the existing holes. From there, I sort-of split the difference so as to ensure a clean cut when I punch out to 8-40 (with an endmill to ensure no deflection) using the Badger specs for spacing.