Support the Site:

M51 Multiple Machine Gun Carriage

Side and rear views of the M51 quad .50 cal. mount and trailer from ORD 7 SNL G-217: Organizational Spare Parts and Equipment for Carriage, Multiple Cal. .50 Machine Gun, M51, Ordnance Supply Catalog, Headquarters, Army Service Forces, October 1944. The M51 was composed of the M17 trailer and the M45 multiple .50 cal. mount.

M51 Antiaircraft Multiple Quad .50 cal. MG Trailer


Continue reading M51 Multiple Machine Gun Carriage

Torpedo Data Computer

Analysis of the torpedo fire control problem and photographs of submarine torpedo data computers from Torpedo Data Computer: Mark 3, Mods. 5 to 12 Inclusive, Ordnance Pamphlet No. 1056, U.S. Navy Department Bureau of Ordnance, Washington, D.C., June 1944:

Torpedo Data Computer

A submarine is equipped with torpedo tubes fwd and aft which are parallel to the longitudinal axis of the ship. When a torpedo is fired it travels in a straight line for a certain distance called the Reach. After it has reached the end of this period of straight line travel, it may be caused to start on a circular course of a definite radius. The length of the circular path is determined by the setting of the gyro in the torpedo and the characteristics of the type of torpedo being used. After travelling in the circular path for a prescribed distance, the torpedo once more assumes a straight path and travels thus until it reaches the target.

The method for controlling the torpedo is by setting the Gyro Angle. It is the function of the Computer to take all of the variable factors into account and determine the value of the Gyro Angle for both fwd and aft torpedoes. The Gyro Angle is continuously generated by the Computer to keep up with the change in the problem due to relative motion of Own Ship and Target.

Submarine Torpedo Aiming and Firing

Continue reading Torpedo Data Computer

Captured Material in North Africa

Analysis of captured German and Italian equipment, particularly newly encountered panzers such as the Tiger tank in Tunisia, remained a priority for Allied intelligence and ordnance teams throughout WWII. The following brief summary of these efforts is taken from “Intelligence Lessons from North Africa, Operation Torch” by the Office of Assistant Chief of Staff, G-2, Allied Force Headquarters, March 1943.

Captured Material

The problem of getting back captured material is a difficult one as fighting units do not have the technical ability to decide what should be sent back and are usually too busy to make the necessary arrangements. In Tunisia, the situation is further complicated as most captured equipment is at once handed over to the French to make up shortages.

The War Department is shortly sending out a team of ordnance personnel trained in the examination of enemy material, to work under the Intelligence Branch at Allied Force Headquarters. It is proposed to have a portion of this team well forward, to be sent to any part of the line where active operations are taking place. They will be responsible for discovering what material has been captured and for ensuring that it is evacuated to the rear as early as possible. The remainder of the team will be at Allied Force Headquarters under the Technical Intelligence officer to arrange for photographs, measurements and dispatch to U.K. or U.S.

It is recommended that similar teams be organized in future for British expeditions with transport including at least one 30 cwt. truck for the removal of material.


Removing Inner Bogie Wheels on Horizontal-Volute Suspension

Instructions for removing the inner bogie wheels on the M4 tank with horizontal-volute spring suspension (HVSS) from Army Motors, Vol. 5, No. 11, February 1945.

Meaning: Horizontal-Suspension M-Four Tank. If that is your brand, this SOP is your oyster.

If you’re an M4-series medium tankman. with a new-fangled horizontal-volute suspension to nurse, you’ve a break comin’ that’ll help with your chores. A new set of special tools just issued to the 2nd and higher echelons makes a couple of tough jobs a damn sight easier—to wit, removing the volute springs from the suspensions, and taking off an inner bogie-wheel.

As you know if you’ve seen them, these horizontal-volute suspensions come with two types of tracks—the T66 with all-steel track-shoes, and the T80 with rubber-shod track-shoes. If you’ve got a T66, you can use the riser block as originally designed, but if it’s a T80, be sure to use the modified riser block. Any or all volute springs can be removed while the center bogie-assembly is raised up on the jack. We posed the T66 for the revealing photos that follow.

When you go to remove an inner bogie-wheel, be sure to leave the hub-caps on throughout the job or you’ll have the wheel-bearings full of grime and grit before you know it—and we don’t have to remind you that spells woe. Another thing—if the outer bogie-tire is worn, you’ll be wise to change it before you start to change the inner bogie-wheel. Then you’ll have good clearance between the wheel and hull, and between the wheel and track on the inner wheel. Carry on.

M4 Tank Track Tools
Fig. 1—Here’s all the special tools you need to do either of these exercises: (A) Block, riser, bogie-wheel, Fed. Stock No. 41-B-1411-200 (before modification). (B) Block, riser, bogie-wheel, Fed. Stock No. 41-B-1411-200 (after modification). (C) Adapters, volute-spring removing, Fed. Stock No. 41-A-30-650. (D) Lock, riser-block, Ord. No. B-7080204. Any other tools you’ll use are OVM or common tools found on your M1 Heavy Wrecker.
HVSS Suspension M4 Tank, Figure 2
Fig. 2—To remove the volute spring, first loosen one wheel-bolt on each wheel of the bogie assembly involved. Place riser blocks, one in front of each wheel of the center bogie-assembly, and hunch the tank forward until the bogie-wheels center on the blocks as you see them here.

Continue reading Removing Inner Bogie Wheels on Horizontal-Volute Suspension

Bazooka Oversold?

Comments on the bazooka from Report of the New Weapons Board, Office of the Commanding General, Army Service Forces, Washington, D.C., April 1944.

2.36" Rocket and Launchers

a. The feeling existed in both theaters that the 2.36" rocket had been oversold. This feeling was accompanied by question as to the effectiveness and accuracy of the 2.36" HE AT rocket. In view of this, the Board incorporated a 2.36" rocket show into each demonstration. The entire renovation of the original launcher and rocket was explained. The explanation included a description of the new wagon-wheel pulpit trap and its function. To demonstrate the safety of the launcher, a launcher which had had two rocket motors exploded within the wire-wrapped portion was exhibited. Two bazookas were then fired at a tank at an 80-yd. range. Amazement was expressed by many spectators at the accuracy and results which were obtained by inexperienced rocket operators. Each demonstration included the firing of six rounds, and it was the exception when there were less than six hits.

b. Many types of eye and face protection have been improvised by combat troops using the 2.36" rocket launcher. Some enlisted men use motorcycle goggles. Others use a modified gas mask, the bottom of which has been cut away; still others use the gas mask as issued. One officer stated that he had obtained excellent results with the use of a plexiglass shield attached to the end of the launcher. Some enlisted men are using celluloid or plastic face shields. Some shields are made to cover the eyes only, whereas others cover the entire face. It was reported that the frustrum of a cone, which had been placed on some launchers, does not serve its purpose. It is believed that this problem should be solved completely and that an item which will afford ample face protection at all temperatures should be developed and issued without delay.

c. Brigadier General Arthur H. Rogers, of the North African theater, reported that early in the Italian campaign a number of the 2.36" rockets carried by his men failed to function. General Rogers stated that these rockets had been carried in ammunition carriers, which hold eight rockets, four in back and four in front. He said that these rockets had been carried fins up, with the fins exposed, and that undoubtedly they had been dragged through mud and water. It was General Rogers’ opinion that the rockets which failed to function failed because moisture entered the motor, although he was not certain that the electrical connection had not been loosened. It is believed that in view of this report the 2.36" rocket should be given thorough proof tests for resistance against moisture. General Rogers also told the Board of a new way in which he employed the bazookas of his organization during the early part of the Italian campaign. He said that he formed bazooka hunting teams. These teams employed 10 to 12 bazookas in one group and went hunting at night. He said that their operation was most successful and that the ambushing of stationary German combat vehicles in this fashion was relatively simple. He spoke very highly of the 2.36" rocket and launcher.


Releasing 76mm Shells for Active Duty

A simple trick for improving the 76mm ready racks in the M4 Sherman from Army Motors, February 1945:

Releasing 76mm Shells for Active Duty


If the 76mm, six-round ready rack or four-round ready rack on your medium tank (in the turret near the gunner’s seat) looks like the one shown in Fig. 1, here’s a simple fix to loosen the ammo.

The end clips (arrow in Fig. 1) hold the shells in the rack good and tight—too tight for fast unloading. So, loosen the top screw and remove the ammo container from the box (Fig. 2). Snap off the clips by bending them back and forth with a pair of pliers or cut the rivets with a sharp chisel. Then turn the box upside down, so the shell holes that were on top are now on the bottom, and slide it back into the rack (Fig. 3).

Repairing M4 Sherman Tank 76mm Ammunition Ready Rack

This is the important thing because inside the shell container there’s a spring that presses down on the shell, holding it firmly. That’s what makes the shell so hard to get out. When the box is turned over, the shell presses on the spring—the pressure’s gone and you can unload lots faster.

There’re several types of six-round ready racks (76mm), so be sure you work this only on the type rack that’s pictured.


How’s Your Sherman, Herman?

M4 Sherman Tank modification and upgrades from Army Motors, Maintenance Branch, Office of Chief of Ordnance, Vol. 5, No. 1, April 1944:

If it’s a Tank, Medium, M4—here are the visible changes that should have been made by now. Check your score—and chase whatever’s missing.

How is Your Sherman, Herman - U.S. Army M4 Tank Modifications and Upgrades

Sorry our list couldn’t quite Tell All. For details on the above additions, subtractions, and modifications, you’ll have to consult the TB’s and FSMWO’s themselves. There are plenty of other TB’s you should have seen, too—full of fascinating facts on M4 operation, identification, lubrication, adjustments, cautions, and assorted SOP’s.

You’ll find all these cataloged in the latest edition of OFSB 1-1, under “pertinent publications” for the Tank, Medium, M4. Anything else is impertinent, including that remark you just made about having so much to read.

Left, top to bottom: New towing shackle-pins FSMWO-G1-W7; New style combat safety lights. FSMWO G1-W9; Disc type track idler wheel. TB 1700-31; Idler brackets. TB 17538-4; Fuel tank filler necks, FSMWO G104-W63; Crowbar bracket relocation, TB 700-48; Mono-gyro control, FSMWO C56-W1; Turret traversing control cam, FSMWO G104-W55; Turret armor plate, FSMWO G104-W57; Azimuth indicator, FSMWO G104-W74; Ammunition rack protector plate, FSMWO G104-W81; Improved turret master switch, FSMWO G104-W82; Gunner’s periscope sight, FSMWO G104-W91; Combination spot and signal fight, FSMWO G104-W92; Smoke bomb thrower, FSMWO G104-W93; Tank commander’s vane sight, FSMWO G104-W94; Impulse firing solenoid, FSMWO G104-W97; Hydraulic hand turret traverse, TB 1731F-1; Lift hooks on gun shield, TB 1758-2; Propeller shaft U-joint tube. TB ORD 12; Track support roller spacer, FSMWO G1-W2; Bogie lift modification, FSMWO G27-W1; Bogie spring bottom seat, TB 700-32; Cast track support roller, TB 700-46**; Bogie wheel bearings and seats, TB 700-72**; Steel track replacement, TB 700-106; Bogie wheel tire sidewalls, TB 1700-36; Bogie and idler wheels (outside U.S. only) TB ORD 22; Hub sprocket capscrew, TB 700-70**; Latest type blackout driving light, FSMWO G1-W6.

Right, top to bottom: Fuel relief valve, FSMWO G104-W65; New type cam assembly, TB 700-52**; Magneto timing change, TB 700-53**; Oil filter replacement elemerts, TB 700-76; Fire detector system, TB 700-98; Interchanging master clutch, TB 731A-6*; Engine oil tank level gage, TB 731 A-7*; Fuel line and accelerator ccntrol rod, TB 731A-11*; Carburetor dust guard, TB 1700-18; Excessive clutch release pressure, TB 1700-35; Bendix-Stromberg carburetor, TB 1725-16; Carburetor economizer seats, TB 1730-1; Valve and magneto timing, TB 1750D-2; Valve and magneto timing, TB 1750D-3; Carburetcr air horn drain plug screens, TB 1751-1; Piston ring change, TB 1751-11; Sealing of engine shroud, TB 1751-12; Valve rocker arm clamp screw, TB 1751-13; Front main Dearing support, T3 1751-17; Autolite generator regulators, TB 731A-10*; Decontaminating apparatus, TB 700-58; Steering lever parking brake, FSMWO G1-W5; Driver’s and ass’t driver’s door lock, FSMWO G104-W75; Hatch guards, FSMWO G104-W83; Clutch pedal interference, TB 700-49; Instrument panel voltmeter, TB 700-68**; Transmission synchronizer assembly, TB 1700-19; Transmission pinion gear shim, TB 1700-22; Transmission clutch gears, TB 1700-23; Differential compensating pinion, TB 1750-4; Transmission oil pump, TB 1750-5.

*Superseded by TM 9-731A (23 Dec. 43)
**Included in TM 9-731A (23 Dec. 43)


Care of Clothing and Equipment

From The Ordnance Soldier’s Guide, 3rd Edition, Ordnance Replacement Training Center, Aberdeen Proving Ground:

RESPONSIBILITY FOR PROPERTY: Clothing and equipment issued to you are government property. If any articles are lost or damaged through your fault or negligence you will be required to pay for them. If you were responsible for the loss or damage, through fault or negligence, then you should admit that fact by signing a “Statement of Charges.” If, however, you believe that you were not responsible, do not sign this statement. In the latter case a “Report of Survey” will be made out and a Surveying Officer will determine whether or not you are to be held responsible. When articles of clothing or equipment have become worn out through ordinary wear and tear, no one is held responsible for the value and the worn articles may be exchanged for new ones.

WWII Care of Soldiers Clothing and Uniform in Basic Training

CARE AND CLEANING OF SHOULDER WEAPONS: Rifle and Carbine—Clean metal parts with sperm oil. Clean bore with rifle bore cleaner or G.I. soap and hot water. Treat stock and hand guards with linseed oil. Treat sling with neatsfoot oil.

WW2 Soldier's Care and Cleaning of Weapons and Equipment

CARE OF TENTING EQUIPMENT: Pegs: Do not hammer pegs into hard ground. Canvas: Brush and dry thoroughly before folding and storing. Rope: Wash thoroughly and dry before storing.


120mm Granatwerfer 42 Mortar

U.S. troops demonstrate a captured Granatwerfer 42 (12cm GrW 42) German heavy mortar on the First Army Front in Echtz, near Duren, Germany.


German Large Caliber Artillery

Table of German heavy artillery in World War II from Catalog of Enemy Ordnance, U.S. Office of Chief of Ordnance, 1945.

Gun*Type of Carriage and TraverseWeight of Equip­ment (lb.)Length of Barrel in CalibersPROJECTILERemarks
Max. Range (yds.)Muzzle Vel. (ft./sec.)Type**Weight (lbs.)
15 cm K. in Mrs. Laf.  4526,0002,730H.E. (15 cm K. gr. 18)94.6Probably used on platform for coast defense
15 cm K. 18 (149 mm)Mod. Box Trail 12°28,4595527,0402,840H.E. (15 cm K. gr. 18)94.6 
15 cm K. 39 (149 mm)Split Trail 60°27,28055.427,0402,840H.E. (15 cm K. gr. 18)94.6Probably mfd. by Krupp
17 cm K. in Mrs. Laf. 18Mod. Box Trail 16°38,5005032,3703,035H.E.B.C. (17 cm K. gr. 38 Hb.)138Krupp, Essen
21 cm Mrs. 18Mod. Box Trail 16°36,7003118,3001,854H.E. (21 cm gr. 18)249Krupp, Essen
21 cm K. 38Field 360°78,0005037,2002,870H.E. (21 cm K. gr. 38)265360° on platform. Krupp, Essen
21 cm K. 39Field 360°74,8004532,8002,620H.E. (21 cm gr. 40)278Skoda design
21 cm K. 39/40
21 cm K. 39/41
       Both reported to be very similar to 21 cm K. 39
21 cm K. 42   37,0002,820  Muzzle brake fitted
24 cm H. 39Field 360°59,4002819,7001,970H.E. (24 cm gr. 39)365Skoda design similar to 21 cm K. 39
24 cm H. 39/40       Later version of 24 cm H. 39
24 cm K. 3 (238 mm)119,00046
41,0003,248H.E. (24 cm gr. 35)331 
24 cm K. 18 (238 mm)Field 6°118,8005540,5003,180 332Fires splined projectile, Rheinmetal Borsig
28 cm H.L./12Static 360°111,0001211,4001,150H.E. (28 cm Spr. gr. L./3.5 m. Bdz.)770Uses DeBange Type obturator. Obsolete except for coastal defense
28 cm Kst. H.Static 360°81,5001212,5001,243H.E. (28 cm Sprgr. L./3.5 m. Bdz.)770Similar to 28 cm. H.L./12. Fires same projectile
35.5 cm M. 1Field165,000 21,9001,870Anticoncrete (35.5 cm gr. Be.)825 
42 cm Gamma Mrs.Static 45°308,0001615,5001,485Anticoncrete (s. Gr. Be.)2,249
Similar to last war equipment
61.5 cm Mrs. 264,000815,3001,380Anticoncrete (gaschosse L./4.1 für Karl gerät)4,400Reported to have an auxiliary 54 cm barrel
15 cm K. (E)Rly. 360°167,0004025,2002,800H.E. (15 cm K. gr. 18)94.6Naval design. Krupp. Same projectile as 15 cm K. 18
17 cm K. (E)Rly. 360°176,0004029,2002,870H.E.B.C. (17 cm Sprgr. L./4.7 Kz. m. Hb.)138Naval design. Krupp
20 cm K. (E) (203 mm)Rly. Turntable 360°189,5005540,0003,030H.E.B.C. (20.3 cm Sprgr. L./4.7 m. Hb.)247Naval design. Also known as 20 cm S. K. C./34
21 cm K. 12 (E)Rly.744,000196131,0005,330H.E.B.C. (21 cm gr. 35 m. Hb.)236Splined projectile. Differences are not known
21 cm K. 12V (E)Rly.       
21 cm K. 12N (E)Rly.      Believed to involve an alteration of the rifling
24 cm Th. Br. K (E) (238 mm)Rly. 1°207,0003522,2002,210H.E.B.C. (24 cm Sprgr. L./4.5 Bdz. u Kz. m. Hb. ung)328Sister piece to “Theodor Kanone”
24 cm Th. K. (E) (238 mm)Rly.209,00040
29,0002,660H.E.B.C. (24 cm Sprgr. L./4.2 m. Bdz. u Kz. m. Hb.)330“Theodor Kanone” Naval design
28 cm Ks. Br. K. (E)Rly.262,0004032,3002,690H.E.B.C. (28 cm Sprgr. L./4.1 Kz. m. Hb.)529Naval design. Carriages are believed to be very similar
28 cm lg. Br. K. (E)Rly.271,0004540,5002,820H.E.B.C. (28 cm Sprgr. L./4.4 m. Bdz. u Kz. m. Hb.)626Naval design. Carriages are believed to be very similar
28 cm s. Br. K. (E)Rly.286,0005040,5002,880H.E.B.C. (28 cm Sprgr. L./4.4 m. Bdz. u Kz. m. Hb.)626Naval design. Carriages are believed to be very similar
28 cm Br. N. K. (E)Rly.330,000 50,2003,260H.E.B.C. (28 cm Gr. 39 m. Hb.)496Probably splined projectile
28 cm K. 5 (E)Rly. 1° Turntable 360°480,0007663,0003,670H.E.B.C. (28 cm Gr. 35)550Weight does not include turntable. Fires splined projectile. Also reported to fire a rocket assisted shell (28 cm R. Gr. L/4.7) with range of 53 miles.
28 cm K. 5/1 (E)     H.E.B.C. (28 cm Gr. 42) Differences from 28 cm K5 are unknown
28 cm K. 5/2 (E)     H.E.B.C. (28 cm Gr. 42) Differences from 28 cm K. 5 are unknown
38 cm Siegfried K. (E)Rly. Turntable 360° 55
61,0003,450H.E.B.C. (38 cm Sprgr. L./4.5) (Si)1,096Naval design. Also fires a 1,764 lb. shell with maximum range of 46,000 yds.
40 cm K. (E) (406 mm)Rly.710,0005049,0003,450
H.E. (40 cm gr. 40)1,320
Naval design—Adolf. K.
80 cm Gustav Geschütz 2,750,0003551,500  16,700 

* Almost all the data given have not been verified by tests performed by any Allied government and information from sources available varies considerably in reliability and degree of confirmation.
** Of the several types of projectiles fired by each weapon, only one believed to give maximum range is listed.

21 cm Mrs. 18:
21 cm Mrs. mit Mrs. Laf. 18: Heavy Howitzer

20 cm K. (E) (203 mm):
20 cm K. (E): Railway Gun