[Lone Sentry: 5-cm Pak 38 Antitank Gun; WWII German Infantry Weapons]
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German Infantry Weapons
Military Intelligence Service, Special Series No. 14, May 25, 1943
[DISCLAIMER: The following text is taken from a WWII U.S. War Department Special Series publication. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


17.  5-CM PAK4 38

a. General

This 50-mm (1.97-inch) antitank weapon5 (figs. 64 and 65) was introduced in the spring of 1941 to replace the 3.7-cm Pak. Mounted on a split-trail carriage and normally towed by a half-track prime mover, it is 01W of the most effective German antitank guns at present in service and is part of the equipment of the German infantry regiment.6

The gun fires armor-piercing shell, high-explosive shell, and armor-piercing shot (AP 40).7 The latter, a light shot with a "windshield" nose8 and tungsten carbide core, has a good performance at ranges under 500 yards. The latest type of armor-piercing shell has a piercing cap.

[Figure 64. 5-cm Pak 38.]
Figure 64.—5-cm Pak 38.

[Figure 65.  5-cm Pak 38 from rear.]
Figure 65.—5-cm Pak 38 from rear.

b. Characteristics

(1) General.—The carriage is provided with a tubular split trail and an armor-plated double shield. The gun has a muzzle brake.

(2) Table of characteristics.
Muzzle velocity:  
     AP    _ _ _ _ _ _ _    2,700 feet per second.
     AP 40    _ _ _ _ _ _ _    3,940 feet per second.
     HE    _ _ _ _ _ _ _    1,800 feet per second.
Maximum range:
     AP    _ _ _ _ _ _ _    1,540 yards.
     AP 40    _ _ _ _ _ _ _    770 yards.
     HE    _ _ _ _ _ _ _    2,640 yards.
Effective range:
     AP    _ _ _ _ _ _ _    880 yards.
     AP 40    _ _ _ _ _ _ _    500 yards.
     HE    _ _ _ _ _ _ _    2,000 yards.
Practical rate of fire    _ _ _ _ _ _ _    10 to 15 rounds per minute.
Over-all length of gun (including breech ring and brake)    _ _ _ _ _ _ _    124.96 inches.
Depression    _ _ _ _ _ _ _    319 mils (18 degrees).
Elevation    _ _ _ _ _ _ _    478 mils (27 degrees).
Traverse    _ _ _ _ _ _ _    115 mils (65 degrees).
Weight (gun and mechanism)    _ _ _ _ _ _ _    675 pounds.
Weight of complete equipment (including extra wheel)    _ _ _ _ _ _ _    2,145 pounds.

c. How to Operate

(1) Safety.—There are three mechanical arrangements which operate as safety devices: (1) unless the breechblock is properly closed, the safety plunger will not enter its recess and the gun cannot be fired; (2) the safety plunger must be in its recess in the lower face of the breech ring before the firing shaft can be rotated; (3) the breech cannot be opened if the striker is not cocked, because the firing shaft is engaged with the safety plunger, which is in its recess.

(2) To load and fire.—To open the breech by hand, recock the firing mechanism by turning the safe-and-fire lever to sicher ("safe") (fig. 66) and pushing it forward again; then turn the breech-mechanism lever in a clockwise direction. The breech will then be held in the open position by the extractors.

[Figure 66. Breech of 5-cm Pak.]
Figure 66.—Breech of 5-cm Pak.

(The spring assembly for the breech-mechanism lever consists of the spring case, which is in two parts (the front with the piston retaining cap and the rear with the piston, piston catch, and pawl), the rack-spindle retaining catch, the rack spindle, the semi-automatic and hand plunger, and the inner and outer springs. When set for hand operation, the piston catch is rotated inwards and the carriage lever does not engage it. The piston head then has the word EIN ("in") showing upwards.)

To load the gun, insert a round smartly. The round will then release the extractors, and the breech will close automatically.

To fire the gun, press the push button in the middle of the elevating handwheel (fig. 67). If this fails, pull the firing lever backward or lift the plunger.

A semi-automatic action operates when the plunger in the center of the front end of the spring case is pressed in and turned so that the word ein ("in") shows upward. When the plunger is set in this position, the breech is opened automatically during the counterrecoil. The gun is always recocked automatically during recoil. The breech is ready to close automatically when a round is slammed in.

[Figure 67. Gunner's position on 5-cm Pak, showing traversing and elevating handwheels.]
Figure 67.—Gunner's position on 5-cm Pak, showing traversing and elevating handwheels.

(3) To open trails.—Push to the right the cradle clamp which fixes the gun in the fully elevated position. The trails being fully open, the weight of the gun is taken off the road springs, and a catch on each side locks the trails in the open position.

(4) Sights.—The sighting gear is operated from the left side and is fitted to the left saddle trunnion. The sight bracket carries an open or telescopic sight, and is provided with a lateral-deflection gear, a range drum, and means of adjustment for line and elevation. Magnification of the telescopic sight is threefold. A battery for lighting the graticules for night shooting is fitted.

The range drum is graduated in black for AP (Pz.) and in red for HE (Spr.). The figures 5-8-10-12-14 on the AP scale correspond to ranges of 500, 800, 1,000, 1,200, and 1,400 meters. Ranges of 300, 700, and 1,100 meters are set on intermediate graduations, which, however, have no figures against them.

The scale for HE is marked 4-6-8-10, etc., up to 24. These figures correspond to ranges of 400, 600, 800, 1,000 meters, etc. Ranges in between are set on the intermediate graduations.

A small lever with a worm screw operates the lateral deflection gear. When a tank approaches directly from in front, the lever should be pointed towards the gunner. If the tank is moving across the line of sight, the lever should be turned two notches in the direction of travel (for example, the lever should be turned to the left for engaging a tank moving from right to left). The lever should be moved only one notch for an oblique target. Lateral deflections may be set in this way for targets traveling at less than 12 miles per hour.

For targets traveling at more than 12 miles per hour the graticules on the sight should be used. The central mark should be employed for tanks approaching from the front, and the left and right laying-off marks for targets moving to the right and left, respectively.

The Germans use the following table as a guide to avoid frequent alteration of the sight during action:
 Part of tank laid on 
1,100 to 880   8 Pz Between top and center of tank.  
880 to 550   8 Pz Between center and bottom of tank.  
Less than 550   8 Pz Center of tank.  

For example, to engage a tank 770 yards away and traveling obliquely to the left at 18 miles per hour, the layer sets the range drum to 8 Pz., moves the lever one notch to the left, and lays the right laying-off mark on the center of the target.

If the telescope is missing, an emergency open sight, held by a lanyard on the right of the sight bracket, can be fitted.

(5) Gun crew.—The Germans have a gun crew of eight, whose duties in firing are as follows:

(a) The chief of section is responsible for seeing that all duties are properly performed, all commands executed, and all safety precautions observed.

(b) The gunner sets the announced deflection, and lays for direction.

(c) No. 1 loads and fires the piece.

(d) Nos. 2, 3, 4, and 5 handle the ammunition.

(e) No. 6 drives the prime mover.

d. Ammunition

The following three types are fired:
  Type     Weight of  
  Length of  
  Weight of  
  Fuze    Identification 
AP tracer shell    9 lbs 3 oz   21.4 in   4 lbs 9 oz   Base  Black, shell case marked 5-cm Pak 38 Pzgr.
HE shell    7 lbs 3 oz   23.7 in   3 lbs 15 oz   Nose (A.Z.39 Dark green, shell case marked 5-cm Pak 38 Spgr.
AP 40 shot1    6 lbs 11 oz   19.5 in   2.025 lbs   None  Black, shell case marked 5-cm Pak 38 Pzgr. 40
1 See paragraph 16 d, p. 118, note 1, above.

e. Maintenance

(1) Stripping.—(a) To disassemble the breech mechanism.—Remove the securing pin from the spring case of the breech-mechanism lever (fig. 66), swing the case to the left and front, and remove the castellated nut and case complete.

Remove the extractor releasing lever, pulling it upwards. Rotate the breech-mechanism lever to the right and rear, thus moving the breechblock and extractors. Remove the extractors (fig. 68) from the left. Close the breech, and set the safe and fire lever to "fire". Press the striker cap in and remove with the spring and striker, which must be uncocked. Open the breech slightly until the key on the actuating shaft is in line with the keyway on the breechblock. Remove the breech-mechanism lever dust cap, pinion, and actuating shaft.

Withdraw the breechblock (fig. 69) and crank. Remove the retaining pin from the firing and recocking shafts. Remove the firing and recocking shafts with the safety plunger.

[Figure 68. Extractors of 5-cm Pak.]
Figure 68.—Extractors of 5-cm Pak.

(b) Recoil cylinder.—The recoil cylinder is mounted in the cradle. The piston rod, which is connected to the gun lug, is hollow and fitted with a bronze piston head. Ports are drilled in the conical part of the piston; a tapered rod is screwed into the front plug of the cylinder and projects into the hollow piston rod.

Counterrecoil control is effected by a brass control plunger screwed to the end of the tapered rod. Toward the end of the run-out, this plunger enters a bore of smaller diameter in the piston rod. Tapered grooves, which are cut in the plunger, graduate the control.

[Figure 69. Breechblock of 5-cm Pak.]
Figure 69.—Breechblock of 5-cm Pak.

(The breechblock is of the horizontal sliding-block type arranged for semi-automatic working. The firing shaft is in two parts. The front has a toe piece engaging the safety plunger, which, when the breech is properly closed, is clear of the toe piece, allowing the plunger to drop into a recess in the breech ring. The rear has a projection which engages the firing plunger. When the breech is closed, the firing shaft holds the firing pin in the cocked position. The recocking shaft has a safe-and-fire lever incorporated which can be operated independently. A recocking lever on the left engages a cam on the cradle during recoil; the right end of the shaft engages the firing pin and, rotating during recoil, it forces the firing pin to the rear. When the safe-and-fire lever is set to sicher ("safe"), the recocking shaft is moved so that a projection on it retains tile firing pin in the cocked position, preventing it from moving forwards. At Feuer ("fire"), the projection is cleared, and allows the front shoulder on the firing pin to engage the firing shaft, ready to fire. The actuating shaft receives the breech mechanism lever at the top, and the crank below. The rack pinion is mounted centrally on it. The crank is fitted with a sliding block which engages a radial groove in the breechblock. The rack pinion engages the rack in the spring case when operated by hand or semi-automatically. The firing pin has a shoulder at the front and a lug at the rear to engage the firing and actuating shafts, and is held in position by a spring. The firing plunger, in the lug on the front lower end of the breech ring, engages the firing shaft when firing. The safety plunger in the breechblock has a cutaway portion to engage the firing shaft. When the breech is properly closed, the plunger can enter its recess in the bottom of the breech ring.

To open the breech, (by hand): First, set the semi-automatic plunger to AUS ("out"). The firing pin has been recocked during recoil. When the breech-mechanism lever is pulled to the right rear, the crank is actuated, forcing the sliding block to the left and thereby opening the breech. The extractors eject the cartridge case and retain the breechblock in the fully open position.

To close the breech (by hand): Release the extractors by loading a cartridge or actuating the extractor releasing lever. The breech should close automatically.

To open the breech (semi-automatic): Set the spring-plunger to semiautomatic. The word EIN ("in") will then show upwards. On recoil a stop fitted to the cradle overrides the piston catch. On run-out, the stop and front face of the piston catch engage, forcing the piston to the rear and compressing the inner and outer springs, until the piston catch is forced inward and the outer spring reasserts itself. The piston with the rack spindle then moves forward under the action of the outer spring, the rack engages the breech-mechanism lever pinion, revolves it, and rotates the breech-mechanism lever to the right rear, so opening the breech.

To close the breech (semi-automatic): Release the extractors by loading a cartridge. The inner spring then asserts itself, allowing the rack spindle to move forward and rotate the pinion and breech-mechanism lever to the closed position.

To fire: The firing plunger is forced upward by a lever on the carriage, which engages the firing lever and rotates it. The firing pin is held cocked by the firing shaft, and is released when the cutaway portion on it is opposite the front shoulder on the firing pin, thus firing the round. The recocking process follows on recoil.)

The piston-rod stuffing box is packed with soft packings. Normal recoil is 700 mm (27.56 inches); metal to metal, 730 mm (28.74 inches). The recoil cylinder should, according to German instructions, be filled until the oil gauge on the near edge protrudes 44 mm (1 3/4 inches).

(c) Recuperator.—The recuperator is hydropneumatic. The hydropneumatic and recuperator cylinders are situated one above the other in the cradle. The recuperator piston rod is fixed to the gun lug.

(2) Assembly.—Assemble the breech-mechanism spring case to the breech ring (fig. 70). Insert the safety plunger in the breechblock. Insert the firing and recocking shafts, securing them by the retaining pin. Fit the crank to the breechblock and place the breechblock in the breech ring.

Assemble the pinion on the actuating shaft with the dust cap and breech-mechanism lever. Fit them to the breechblock, with the pinion engaging the assembling line on the rack, and the key on the actuating shaft in line with the keyway on the breechblock. Place the striker, spring, and cap in the breechblock.

[Figure 70. Barrel and breech of 5-cm Pak.]
Figure 70.—Barrel and breech of 5-cm Pak.

(The barrel is of monobloc, loose barrel construction and is fitted with a muzzle brake. The breech ring is rectangular and is secured to the barrel by a locking collar. A clinometer plane is provided. The recuperator system is attached underneath the breech ring by a detachable lug. The extractors are fitted to, and kept in position by, an extractor releasing lever which passes through the breech ring.)

Assemble the extractors to the breechblock, and push the block to the closed position until the extractor releasing lever can be inserted.

f. Carriage

The carriage is of the split-trail type carried on two disk wheels, with a third detachable wheel to increase the speed of bringing the gun into action. The carriage consists mainly of the following:

(1) Trail.—The trail has split tubular legs. The right leg has a cradle clamp near the front and a traversing stop. The left leg is fitted with a stop for the cradle clamp and a lunette and locking bolt, so that the legs can be locked together for traveling. Each leg has a spade, lifting handle, and traversing handle.

(2) Axle.—The axle houses a pintle to which a traversing rack is fixed. The ends are cranked forward to take the wheels.

(3) Saddle.—The saddle supports the cradle and gun, and is pivoted to the axle. The sighting gear and layer's guard are mounted on the left trunnion and a hydropneumatic compensating cylinder is fitted to the right. The function of the cylinder, filled with air under pressure and a small quantity of liquid, is to balance the cradle and piece, which are muzzle-heavy.

(4) Cradle.—The cradle houses the recoil cylinder and recuperator. The semi-automatic cam arms which engage the recoil cylinder stop on the breech-mechanism lever are bolted to the left side.

(5) Elevating gear.—The elevating gear gives 27 degrees (478 mils) elevation and 18 degrees (319 mils) depression. It is operated by a handwheel on the left side of the carriage.

(6) Traversing gear.—The traversing gear is operated from the left side of the carriage and allows about 32 1/2 degrees (565 mils) traverse left and right (a total of 65 degrees (1,151 mils)).

(7) Sighting gear.—The sighting gear is operated from the left side and is fitted to the left saddle trunnion.

(8) Cradle firing gear.—The cradle firing gear is operated from the elevating handwheel. A push knob, to which is attached a cable, actuates the firing mechanism.

(9) Shield.—The shield consists of two 4-mm sheets of armor plate spaced about 1 inch apart. The left side of the shield has a sight port.

4 Panzerabwehrkanone ("antitank gun"); see par. 16a, p. 113, note 2, above.
5 The German tactical symbol for the 5-cm Pak is [5-cm Pak Symbol] or [5-cm Pak Symbol].
6 See fig. 1, p. xii, above.
7 See paragraph 16d, p. 118, note 1.
8 Ballistic cap.

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