(1) Characteristics.--The Vickers-Armstrong 2-pounder antitank gun Mark I is a semiautomatic caliber 40-mm (1.58 inches) weapon with a muzzle velocity of 2,616 feet per second. It has a 5/16-inch armor-plate shield, which will keep out ordinary small arms fire but will not repel the armor-piercing bullets fired from tank machine guns. It is carried on two rubber-tired wheels, towed by a 3/4-ton truck. For firing, it is lowered to, three outriggers.

Figure 9.--British 2-pounder antitank gun in position in the Western Desert. (This photograph gives an indication of the height of the gunner's sight.)

(2) Operation.--The gunner's position is on the seat to the left of the gun. The vertical handwheel on the left controls elevation. The trigger control is attached to this handwheel. Traversing is accomplished by a horizontal handwheel to the right of the gunner. For rapid traverse, a throw-out clutch at the right foot of the gunner allows the NCO gun commander to traverse the gun, pedestal, and gunner together by pressing on the shoulders of the gunner. The carriage gives the gunner every advantage. It is a fine gun to shoot on the practice range, but its extreme height is most noticeable. In country with thick underbrush there are some positions where such a carriage is advantageous, but in the desert the lower the carriage when firing, the better.⁸

Three independent sights are provided. The first, a simple ring and bead type, is used by the NCO gun commander for approximate setting. The other two sights are used by the gunner. The telescopic sight has a field of approximately 20°, and a magnification of about four times. There is a fixed vertical line and movable horizontal line with range marks at the left for 300, 600, 900, 1,200 and 1,500 yards. A small knob directly above the sight, provided with a click, permits movement of the horizontal line by increments of 100 yards. This operation is performed by the NCO gun commander after initial setting by the gunner in accordance with the oral instructions of the commander. Mounted on and above the telescopic sight is a forward bead sight and a rear notch-type sight, adjustable in elevation. Attached to the left side of the pedestal is a receptacle for a spare telescopic sight.

(3) Portee.⁹--In order to increase the mobility of the 2-pounder antitank gun, the British have been employing it portee on a 1 1/2-ton truck. A recent development has been a type of light self-propelled or assault artillery in which the 2-pounder antitank gun is mounted on the Loyd carrier. The regular shield of the 2-pounder is utilized for protection against small arms fire from the front, and additional protection is provided by armor shields on the sides of the gun. The tires of the portee and of the gun are of the "run flat" type. To prevent rocking of the portee and to enable the crew to carry out their duties efficiently, the gun when used from the portee is not fired at an angle greater than 40° from astern. This requires perfect understanding between the gunner and the portee driver.

b. 6-pounder

The 6-pounder antitank gun has been designed by the British for use against enemy armored vehicles which are not vulnerable to the 2-pounder at distances of over 200 or 300 yards. A 57-mm gun, the 6-pounder will be able to engage tanks at much greater ranges than the older 2-pounder, although the latter will still be important to the antitank defense of individual formations and units. In order to facilitate the quick adoption of the proper gun for the circumstances, the carriage of the 6-pounder is so designed that the 2-pounder may be mounted alternatively. It is intended that the 6-pounder will be standard equipment in the divisional antitank organization.

Figure 10.--British 6-pounder antitank gun (two views)

c. 25-pounder Field Gun-Howitzer

Fire from the British 25-pounder (3.45-inch) field gun-howitzer, the basic field piece of the British Army, has been extremely effective for two reasons: (1) the 25-pounder is an excellent field gun, and (2) British artillery was well-trained before the outbreak of war. German tanks when struck by 25-pounder armor-piercing shell at ranges less than 1,000 yards have sometimes been knocked out; some have had turrets completely blown off, and others have been set afire. Indirect 25-pounder fire is, however, not effective for stopping tank attacks, but it can cause the tanks to "button up" their hatches. Reports of indirect fire's stopping tank attacks are believed to be erroneous interpretations of the repulse of reconnaissances in force.

Figure 11.--Diagrammatic sketches of British 25-pounder field gun-howitzer, showing its characteristics (with British terminology)

Figure 12.--British 25-pounder field gun-howitzer, showing the method by which it is transported

The 25-pounder has been replacing both the 18-pounder and the 4.5-inch howitzer of the last war. The tube has a removable liner which can be changed in the field. The gun can be placed in firing order on its platform in 1 minute. The firing platform is in the form of a wheel which is carried either under the trail or on the back of the prime mover. To place the piece in action, the platform is lowered to the ground and the carriage is then manhandled or tractor-drawn over it and coupled to its center. To permit easy maneuvering of the trail, the spade has been imbedded in a "box" commonly called a "banana," which functions very effectively and prevents the trail from digging in. The muzzle velocities with its three normal charges are 650, 975, and 1,470 feet per second, and with supercharge 1,700 feet per second.

d. 4.5-inch Gun and 5.5-inch Gun-Howitzer

(1) General.--The 60-pounder has been replaced by the 4.5-inch gun; the 6-inch howitzer is being replaced by the 5.5-inch gun-howitzer as the latter becomes available. The two new weapons are mounted on the same type of carriage, which has a split trail and is simple and easy to use in going into and out of action. While the guns are being fired, the three points of support are the center of the axle and the two trail spades. When the trails are closed, a simple locking mechanism automatically locks in traveling position the carriage proper, the traveling axle, and the trails. Although the trunnions are well to the rear and equilibrators are provided, the recoil mechanism is variable. In addition, the carriage has a quick-release elevating mechanism which permits the tube to be placed in the horizontal position for loading while the elevating rack remains properly laid for the desired target.

(2) 4.5-inch gun.--This gun fires a 55-pound shell and has a muzzle velocity of 2,265 feet per second.

(3) 5.5-inch gun-howitzer.--This medium gun-howitzer fires a 100-pound shell and has a muzzle velocity of from 1,235 to 1,675 feet per second.

e. 6-inch Howitzer

This is a medium howitzer with muzzle velocity of from 1,235 to 1,352 feet per second. It is made of steel (wire construction) and has a calibrated sight. The breech mechanism is of the Asbury single-motion type, having a parallel breech screw of the Welin pattern.