Micro-Lapping the Remington 700/40X Receiver Bed

Where a cylindrical action contacts the stock bed, the fit is not always as precise as it should be. This lack of precision is frequently seen in a number of actions like the Savage, Weatherby, Remington, and others. Here, I’ll describe the construction and use of a precision lapping tool for the receiver bed of the popular Remington Model 700- Series rifle and its direct descendant’ the Remington Model 40X.

The tool is designed to microscopically improve the bedding on all types of Remington stocks’wood, graphite, or fiberglass’or where glass bedding, pillar bedding, or an integral bedding block is used. Making the Bedding Lap The body of the lapping tool should be made of metal or high-impact plastic. I chose apiece of iron rod stock. Select apiece with a diameter large enough to turn it on the lathe to a diameter of exactly 1.332 inches.

With a finished length of 7-7/8 inches long, the tool will service both the short and long actions. The part should be cut square at each end, without rounding of the edges any more than is needed to relieve sharpness or remove burrs. A Remington Model 700/40X receiver is 1.353 inches in diameter and this tool is designed to be used with 3M Company silicon carbide 240LPS wet or dry abrasive paper, or the like.

This sheet is 0.010 inch in thickness, and when singly wrapped over the lapping tool, yields aside-to-side diameter of 1.353 inches’t he same as the action. 332-inch diameter and 7-7/8-inch length. Keep a close tolerance here. Following this, drill and tap two 1/ 4-inch holes about an inch from each end for top-guide handles. These can be made of any material strong enough to do the job.

A through hole in apiece of plastic, wood, or steel will do, or if metal is used, just drill and tap a hole to fit the 1/4-inch threaded holes in the tool body and handle. I just happened to find a couple of decorative locking handles already tapped at one end. Using the Micro-Lapping Tool Place the rifle stock in a padded vise so it is steady and easy to reach. Cut apiece of abrasive paper to the exact length of the lapping tool and wide enough to extend upward beyond the inner borders of the stock.

To hold the paper snugly on the lap, a full length of double-sided tape does a good job. Be sure this is on the lap well above the stock so the radius dimension isn’t altered. Set the tool squarely into the stock so the front is at the forward aspect of the receiver-ring bed and the

Above left and The author happened upon these fancy handles while making the tool, but two long machine screws would suffice. Wet-or-dry 240grit abrasive paper is used between the stock bed and the lapping tool. rear is at the tip of the stock-bedding tang. Then, with very light, downward pressure at each end of the lapping, make very short back and forth strokes’just a few to start with. Remove the tool from the bed and examine the paper and the stock bed for contact where any material has been removed.

The black paper will readily show where the stock bed has been altered. It also shows precisely where the bed needs to be altered as high spots are sanded down. These high spots are the cause of uneven, accuracy-robbing action bedding. In this process, we’re not trying to remove an appreciable amount of bedding material, regardless of whether it’s wood, metal, or fiberglass. We’re just trying to produce a microscopically uniform fit between the receiver and the stock.

Unbeknownst to many shooters, poor action bedding can be the cause of poor groups on target. That’s because a poor fit can allow "springing" of the action, producing vibrations that can destroy accuracy. A good test for uniform contact between the stock and receiver is to alternately loosen and tighten the action screws fore and aft. When turning a screw, feel for any perceptible movement where the action meets Shown here are two five-shot groups fired from a 270 Winchester heavy-recoil rifle.

The Model 700 action was bedded to its stock using a bed lapping tool described in the text. the stock using thumb or finger pressure at this juncture. It’s amazing how little stock-to-receiver movement can be felt in this way. If the center screw on a Remington or any other threescrew receiver is used, it should receive only moderate torque unless a bedding pillar is used at this area of the stock.

Conclusion While the cost to make this tool is negligible, it’s easy to make and use, and should become apart of any gunsmith’s "bag of accuracy tricks." Micro-bedding is an important part of the workup on any target rifle, and the ultimate accuracy cannot be achieved without it. I