Installing a Forend Barrel-Tuning Device

In carefully controlled tests with rifles capable of sub-half-minuteof-angle accuracy, I found the stock-forend barrel-tuning device to be a definite aid to improving performance. In no case did such a device worsen accuracy. These tests were conducted using Remington Model 40X rifles, factory equipped with these devices. These included calibers ranging from .222 Remington through 6mm and some larger calibers.

This article will cover installation of triangularly positioned, adjustable bedding screws placed in the forend of a Remington Model 504 in .22 LR caliber. Five different barrels were The smaller, secondary holes for the adjusting screws are cut later. Below center: This inside view of the stock forend shows the barrel-tuning devices installed. This view and the inside view clearly show the necessary angle of the tuning devices for proper barrel contact.

Properly sized endmills or piloted countersinks do a perfect job in fitting the parts. fitted to the action of this rifle used in testing. For bedding screws, I used a pair removed from a Model 40X Remington which were reduced in diameter at the internally threaded sleeve that retains the screws. The 5/16-inch screws have 32 threads per inch, which provides a thrust of 0.031 inch per turn of the screw.

The tuning screws are positioned about an inch back from the forend tip and 9 inches forward of the barrel/receiver juncture. In actual use with match ammunition, a half turn on each of the tuning screws, after barrel/screw contact, moved the bullet’s point of impact upward 3 inches at 50 yards. A

full screw turn moved it up 5 inches. The target included shows how bullet point-of-impact and accuracy responded to the use of the tuning screws in this instance, which is quite representative of other barrels and bullets used. Careful attention must be exercised in positioning the threaded sleeves that retain the tuning screws. You must be sure the thrust angle is correct, and that ample space in the stock is available. Most target-type stocks pose no problem, while many sporter-type stocks may.

I was able to position the screws at a near 45-degree angle in the Remington 504, resting square with the barrel and spaced outside at 1-3/8 inches. Inside the stock forend, the screws are spaced about an inch from center to center. I used endmills to make the holes, which cut perfectly clean holes. This involves a two-diameter hole’one inside the stock for the screw sleeve, and one for the extended adjusting screw which passes through the outside of the stock. The correct size endmill must be used for each hole.

Be sure the sleeve hole is cut to the correct depth so the surface of the sleeve clears the barrel channel inside. Normally, free-floating barrels provide ample space here. The bottom of the sleeve will rest firmly on the clean-cut hole made by the endmill or other hole cutter, and if the sleeve is knurled, a slight tapping will hold it in place. Where the hole is a bit larger than the sleeve, some form of bonding agent may be required to hold it securely.

A small amount of silicone adhesive will do as a more permanent bond would make removal of the sleeve quite difficult. I chose to mill out a channel 1/2 by 1/2 inch at the bottom of the forend from the adjusting screws back to near the receiver ring. This slot is for apiece of metal to stiffen the forend, which is bonded into place with stockbedding material or the like. I used Brownells Accu-Bond, which hardens solidly with no appreciable shrinkage.

Cleaning up the edges of the stock An equally effective method is to turn each screw-to-barrel contact, and then advance the screws the number of turns required for best accuracy. where the adjusting screws are positioned may be required, including a bit of stock finish. Adjusting the tuning screws is simple, although each rifle and barrel, along with its load, is likely to respond somewhat differently to screwto-barrel pressure.

However, in the case of the Remington Model 504, setup with the tuning screws about 9 inches forward of the receiver, from one-half to a full turn showed the optimal accuracy improvement. This may vary somewhat with installation application, as well as with different rifles, barrels, and ammunition. To determine barrel-screw contact, a thin feeler gauge can be placed between the screw and barrel. As a slight resistance is felt, this will represent the starting point of adjustment.

As I have found, a tactile approach works perfectly well, too. Grasp the barrel and forend in such away that the thumb touches both parts. Advance one screw until perceptible movement is felt, and stop there. Then do the same with the other tuning screw. From there, simply advance the screws against the barrel uniformly. A quarter or half turn will show a significant change in bullet impact on target.

Installation of the forend barreltuning screws shows a definite accuracy improvement in the Model 504 Remington, as it has in other rifles where these devices were installed. The adjusting screws are easy to install with common shop tools, and the cost is minimal. Such adjusting screws can readily be manufactured as custom parts using a 1/4-inch fine thread into a knurled and threaded sleeve. In any case where improved accuracy is sought, this approach should be considered. I