50-mm Light Mortar, German (WWII U.S. Intelligence Bulletin, January 1943) (original) (raw)

50-MM LIGHT MORTAR (German)

1. GENERAL

The standard light mortar of the German Army is the 50-mm. This is comparable in a number of ways to our 60-mm, although ours is the superior weapon on the whole, especially as to maximum range, precision, and all-around performance.

The following table affords a basis for a comparison of the two weapons:

| | German 50-mm Mortar | U.S. 60-mm Mortar | | | ------------------------ | ---------------------------------------------------------------------- | ------------------------------------------------------------------------------------ | | Caliber | 50 mm | 60 mm | | Weight in action | 31 lbs | 42 lbs | | Length of barrel | 18 in | 28.6 in | | Maximum range | 568 yds | 1,935 yds | | Minimum range | 55 yds | 100 yds | | Traverse | 600 mils (change in deflection) = 33°45' | 140 mils (70 either way) = 7°57' | | Rate of fire | 6 rounds can be fired in 8 seconds. but this rate cannot be maintained | Maximum: 1 round in 2 seconds; normal: 1 round in 4 seconds — this can be maintained | | AMMUNITION FOR ABOVE | | | | Type of bomb | HE | HE | | Overall length | 8.5 in | 9.54 in | | Maximum diameter | 50 mm | 60 mm | | Weight | 2 lbs | 2.96 lbs | | HE filling | TNT | TNT | | No. of charges, or zones | 1 | 4 | | Propellant | Nitrocellulose | Nitrocellulose | | Markings | Bomb painted dull red, stenciled in black | HE, yellow; practice, blue | | Fuze | Percussion | Superquick |

The 50-mm is muzzle loaded and trigger-fired, and is designed for high-angle fire only—that is, for fire at angles of not less than 45 degrees. Our 60-mm is muzzle-loaded, has a smooth bore, and is not trigger-fired. It is designed for high-angle fire at angles of from 40 to 85 degrees.

Figure 1. German 50-mm Light Mortar.

Although sights will be found with German 50-mm mortars manufactured before 1938, the mortars manufactured during or after that year are laid on the targets or aiming stakes by means of a white line on the barrel. Our60-mm has the M4 sight, as does our 81-mm mortar.

Figure 2. Another View of the German 50-mm Light Mortar.

The 50-mm is a two-man load. One man carries on his back the base plate with traversing and cross-leveling gear. The other carries on his back the barrel and the elevating screw pillar. Our 60-mm is a two-man load, also; a corporal carries the base plate and sight, while the No. 1 man carries the mortar and bipod.

2. ELEVATION

Range for the 50-mm is indicated on an arc fixed on the left side of the barrel by the rear edge of an indicator hinged on the traversing bracket. The arc is graduated from 60 to 520 meters, and the indicator can be folded down when the mortar is dismantled.

A rough adjustment of elevation can be effected in the following manner: Pressing a quick release lever unlocks the catch of the sliding collar connected to the upper end of the elevating screw pillar. The collar is then free to slide along its guide and the barrel can be elevated by means of the barrel handle.

As soon as the range ordered is approximately indicated on the range scale, the sliding collar is locked in its guide by the release of the quick-release lever. Fine adjustments are effected by rotation of the sleeve of the elevating screw pillar.

The U.S. 60-mm mortar has a permanent firing table, which is fitted to the tube. For ammunition of present manufacture, a firing table card is included with each complete round container. This table gives elevation (degrees) corresponding to various ranges throughout the field of fire, and also gives the change in deflection (mils) due to one turn of the traversing control of the mount. The latter feature permits direct introduction of deflection corrections in case the sight is lost or becomes unserviceable.

3. LINE

The mortar can be laid either direct or by means of aiming stakes. Rough adjustments for line are effected when the position of the base plate is altered, with the traverse set at zero.

A deflection scale is engraved on the cross-bar joining the two leveling handles, and consists of a double row of graduations. The interval between the graduations in row is 20 mils, but the rows are offset, so that the graduations on one are halfway between the graduations in the other. Thus the scale indicates deflections to the nearest 10 mils.

The total traverse is 600 mils (33° 45')—that is, 300 mils (16° 52' 30") each side of zero. Fine adjustments are made by rotation of the traversing handwheel until the required deflection is indicated on the scale.

4. LOADING AND FIRING

During loading and firing of the 50-mm mortar, the layer's position is on the left, behind the mortar. He lies on his belly, holds the leveling handles, and presses on the base plate with his forearms. The loader, who lies to the right of the layer, loads by inserting the bomb in the muzzle, tail down.

After releasing the bomb, the loader's right hand instantly goes to the trigger, and both loader and layer lower their faces to the ground. Meanwhile, the layer still holds the leveling handles and continues to steady the base plate by resting his weight on it. On the order to fire, the loader pulls the trigger slowly and evenly the rear.

5. MISFIRES

When a misfire of the 50-mm occurs, the trigger should be pulled again—several times, if necessary. A German training manual warns that the detachment should wait 1 minute before unloading, in order to avoid accidents caused by possible delayed fire. On the other hand, when a misfire of the U.S. 60-mm occurs, the No. 3 man immediately strikes the barrel several times with a heavy nonmetallic instrument, such as a 2- by 4-inch timber, or, if this is not available, with the cleaning rod or with his heel. The mortar crew then waits at least 1 minute before removing the round.

6. AMMUNITION

The bomb fired from the 50-mm is a streamlined H.E. bomb of the anti-personnel type, with a finned tail unit which carries the cartridge. The bomb is fitted with a quick-acting nose fuze with booster. (The German name for this bomb is the 5-cm. Wgr. 36.)

The body is of mild steel with walls 4-mm thick, and has a cylindrical portion near the head. A screw-threaded fuze hole is formed at the head, and the base end is similarly prepared to receive the cartridge container portion of the tail unit. The body contains a bursting charge of T.N.T. weighing approximately 4 1/2 ounces.

The tail unit consists of a mild (not hardened) steel cartridge container, to which 8 blades formed in pairs, are spot welded to form the fin.

The fuze (Wgr. Z. 38) is a quick-acting nose percussion fuze with a graze pellet and booster. It arms itself approximately 60 yards from the muzzle of the barrel; until then it is safe.

The U.S. 60-mm mortar uses an H.E. shell (designation: Shell, H.E. M49A1, w/ PDF M52, 60-mm mortar) against personnel and light materiel targets. The action of the fuze is superquick. For use in the field, it is issued assembled to the shell as a component of the complete round. To arm the fuze, it is necessary only to remove the cotter pin.