Description

“Clip Slotting” is the popular term for modifying the M700 receiver to accept an optic base made for one of the following:

M40
M40A1
M40A3
DARPA XM-3

The purpose of this is to attach the scope base to the receiver in a manner that keys the receiver and base as one piece. The combination of lug and keyed surfaces deliver an extremely robust and dependable mount. The screws are left with the sole function of merely holding the two together.

The action is modified so that the scope base lug surfaces slip into the registers machined into the receiver. In addition, the ejection port is lengthened and altered to form the double radius feature. This is often referred to as the “thumb slot.” There are two versions of this feature. We know of no official name, so we made our own. Scope base mount holes are increased to the #8-40 size on the receiver for both.

The “Single Thumb Cut”
The “Double Radius”

Our tool paths are based on original Remington drawings; to include the small detail items like the subtle alteration of the receiver body along the ejection port between the rear bridge and front ring.

As the drawing shows, the original M700 profile is altered slightly, yet there are no dimensions to define the feature. As with many government small arms contracts, a number of private companies are retained to perform this work. What is “right” is often based on who was satisfying the contract at the time. The consequence from this as a collector are that these guns are often subject to broad opinion based on very muddy facts. There is very little documentation available.

NOTE:

There are multiple companies offering bases for this alteration. They are NOT all the same, even when sourced from the same manufacturer! Because of this, we have a strict policy that we will only perform this work when we have the actual part being installed. We were once retained to do this work on an assortment of receivers with a single scope base supplied by the client as the artifact. We were later informed that the other bases purchased did not fit because none of them had the rear base holes in the same location relative to the lug features.

A hard lesson in this trade: “Trust but verify.”