Making an Action Wrench For the Weatherby Mark V

Over a period of years, I’ve converted a number of rifles to switch-barrel use. These have included the Winchester Model 70, Remington 700-Series, Remington XP-100, and Remington Model 40X bolt-actions, as well as some breakopen-type actions. Each bolt-action type required a different style action wrench to properly fit the receiver. And, with each action type, I wanted to be able to remove the barrel and install different ones without disturbing the action in the stock or removing the scope from the receiver.

Thus, a special action wrench and torque bar were required to make this possible. Making an action wrench to fit the normal bolt-action locking-lug raceways presents no special problems. The laterally opposing lugs on these wrenches slide inside the milled action raceways like a rifle bolt, and engage in the forward area of the receiver where torque is applied to the wrench. The action wrench used on the Weatherby Mark V, however, is quite different by design.

Here, the extreme diameter of the radially positioned bolt-locking lugs is the same as the bolt, which is 0.700 inch for the standard-cartridge receiver. Though unique in construction, making such a wrench to fit the Weatherby action is not complicated. Nevertheless, detailed directions will make the job much easier than using the trial-and-error method. The principle involved here finds the three locking lugs on the action wrench engaging the sides of the three pairs of locking lugs inside the Mark Vaction.

The three wrench lugs engage the six receiver locking lugs from the sides (radially), whereas the rifle-bolt lugs engage the receiver lugs in a conventional way (axially). The wrench for the Weatherby Mark Vis third from the top. With the barrel removed from the Weatherby action, a close look from the threaded end shows the three pairs of triangularly positioned locking lugs. You will note these pairs of lugs are not equally positioned.

The top pair is positioned at 12 o’clock, the lower-right one is at about 4:20, and the left lower one is

Above center: The lugs are formed at the end of the Weatherby action wrench with a 3/8-inch ball-end mill. at approximately 8 o’clock. Don’t let this discourage you, because marking and cutting the raceways in the head of the action wrench to match the receiver-locking lugs is very easy. First, I had already turned the main action wrench to a diameter of 0.700 inch and a length of 8.5 inches, and formed the end for a 1/2-inch socket-wrench drive.

Then, with the shaft inserted into the receiver bolt hole, you can look right into the receiver and see the end of the shaft resting against the recoil lugs. From this position I immobilized the shaft by turning an action screw against it. I then carefully marked around the borders of the receiver-locking lugs on the butt surface of the action wrench. Either a very fine felt-tipped pen or a sharp metal scriber will work well for this.

The shaft is then placed horizontally in the mill vice and a 3/8-inch In the center is the action wrench along with the socket-wrench coupler. At the top is the torque bar with a 1/2-inch socket-wrench drive. ball-end mill is used to form the end grooves in the action wrench that engage the receiver-locking lugs. Actually, the sides of the receiver-locking lugs are at nearly a 45-degree angle, and these form an almost perfect fit to the radius groove cut by the 3/8inch ball-end mill.

Then, as the first top-end groove is cut to a length of about 5/8 inch and a depth of 0.130, the shaft should again be inserted into position to check for precise alignment of the groove with the locking lugs. This is a good time to check if your marks are correctly positioned for the next mill groove. This procedure is followed until all three grooves are cut. At this time, try the wrench for fit into the receiver-locking lugs.

Here is where you will see the receiver-locking lug lateral surfaces are at a 45-degree angle, which fit nicely into the rounded, milled grooves in the head of the action wrench. Careful inspection will indicate where, if any, additional spot milling may be required to ensure uniform contact

The torque bar is coupled to the action wrench with a 1/2-inch socket wrench. at all surfaces within the grooves. Though this procedure may appear complicated, it is not. Each rounded mill cut should be close to a depth of 0.130 inch. There is a good chance the head of the action wrench will fit quite well as you first try it. If not, you will be able to clearly see where a shave of metal must be removed with the end mill for a proper fit.

Where there is a snug fit, the use of a small brass hammer to tap the end of the action wrench against the lugs will show where additional milling is required. I achieved a nearly perfect fit on the second try in this way. Coupling of the action wrench with the main torque handle is accom These barrels are fitted and headspaced to the Weatherby action.

From the left is the Broughton barrel in .257 Ackley Improved, the Weatherby/ Krieger barrel in .243 Winchester, and the Weatherby/Krieger barrel in .22-250 Remington. plished via a standard 1/2-inch-drive socket wrench. This end of the wrench can be made to 1/2-inch square drive or a hexagon to fit a six-point socket. I’ve made these wrenches for others and have used both the 1/2-inch square end as well as an 11/16- and 3/4-inch hexagon drive.

Where a 3/4-inch hex drive is used, I simply turned an 8-1/2-inch piece of hexagon shaft to the required 0.700 diameter and left a 1-inch hexagon end on it. Of course, you’ll need a suitable barrel vise as you switch barrels and the torque bar. The padded barrel vise was covered in the March 2003 issue of American Gunsmith, and this vise works very well. As a torque bar, all you’ll need is a 1/2-inch-square stud 1 inch long, welded at the center to a 2-foot length of 3/4-inch bar stock.

I’ve experimented with various amounts of applied barrel torque in arriving at a workable axial preload (torque pressure at the barrel receiver joint). I’ve found this can vary all the way from 75 foot-pounds to well over 140 foot-pounds with little, if any, noticeable changes in point of bullet impact and accuracy, or cartridge headspace. You must strive for uniformity, however, as torque is applied. It’s much like tightening the lug nuts on your automobile rims— common sense and "feel" go along way.

I’ve monitored barrel torque with a special torque wrench and discovered a fair amount of leeway is permissible. While at the Weatherby plant at Brainerd, Minnesota, I learned that 120 to 140 foot-pounds of torque is applied to the barrels on Mark Vactions used for standard rifle cartridges. I use some thread lubricant when switching barrels, and the type is not critical. A light coating of heavy oil or white-lube on the barrel shoulder and the threads works out well.

I’ve never had a barrel loosen while shooting, or change torque, even after extended use. Under closely controlled conditions, I’ve removed a barrel and replaced it while shooting a five-shot group, and the group remained under one minute of angle. Conclusions If the only thing standing in your way to converting the Weatherby Mark Vaction to switch-barrel use is an action wrench, this is a small hurdle to overcome. Anyone with average shop experience can make his own, and the cost is very low. ■