American Projectiles and Explosives - 20mm Projectiles

American Projectiles and Explosives

20mm Projectiles

20mm A.A. H.E., H.E.I., and B.L. & P. Mk 3 Mods 1-64

Overall length w/ nose fuze: 3.275 inches
Overall length w/o nose fuze: 2.625 inches
Diameter of base: 0.74 inches
Distance base to band: 0.374 inches
Width of band: 0.16 inches
Diameter at bourrelet: 0.78 inches

Filling:
-H.E.: 0.0243 pounds Tetryl or Pentolite
-H.E.I.: 0.0072 pounds incendiary mix; 0.0171 pounds Tetryl of Pentolite

Weight of loaded projectile: 0.2714 pounds
Charge/Weight ratio: 8.9%

Cartridge case:
-H.E.: Mk 2
-H.E.I.: Mk 2, 3, or 4

Primer:
-H.E.: Mk 30
-H.E.I.: Mk 30 or 31

Tracer: N/A

Fuzes:
-Nose: Mk 26 Mods 0 and 1


The explosive filling of the H.E. projectile is press-loaded in three equal increments.  The H.E.I. projectile is similarly loaded, but the first increment consists of an incendiary mixture, the other two of H.E., either Tetryl or Pentolite.

This round is also issued B.L. & P., with an inert filler and a dummy nose cap.



Identification and Markings

Type ---- Color

H.E. (Tetryl) ---- White
H.E. (Pentolite) ---- Yellow
H.E.I (Tetryl) ---- Red
H.E.I. (Pentolite) ---- Light Pink
B.L. & P. ---- Dark Gray Green

The many modification numbers are to distinguish between products from different contracts.







20mm A.A. H.E.T., and B.L. & P. Mk 4 Mods 1-28 and Mk 7

Overall length : 3.025 inches
Overall length w/o nose fuze: 2.525 inches
Diameter of base: 0.74 inches
Distance base to band: 0.397 inches
Width of band: 0.16 inches
Diameter at bourrelet: 0.78 inches

Filling:
-H.E.: 0.01 pounds
-Tracer: 0.0173 pounds

Weight of loaded projectile: 0.2621 pounds
Charge/Weight ratio: N/A

Cartridge case: Mk 2
Primer: Mk 30
Tracer: Integral

Fuzes:
-Nose: Mk 26 Mods 0 and 2 (Mk 4)
-Nose: Mk 26 Mods 0 and 1 (Mk 7)

 Length of tracer cavity: 1.107 inches
Diameter of tracer cavity: 0.51 inches

To eliminate the blinding flash characteristic of standard 20mm tracers fired at night, a special Dark Ignition tracer has been developed which does not light up until about 100 yards from the gun muzzle.  Rounds are designated "H.E.T.D.I."  Overall burning time of this tracer is four seconds; during the "dark" period there is a faint streaking in the projectile's path.

The Mk 4 and Mk 7 rounds are identical except for the dimensions of the tracer cavity, which is slightly greater in diameter and length in the Mk 4 than in the Mk 7.  This somewhat reduces the tracer filling of the Mk 7.

The Mk 7 round is also issued B.L. & T. with an inert filler in the H.E. cavity and a dummy nose plug.  The tracer cavity contains the standard tracer mixture.

The burster charge of the 20mm is more sensitive than the usual projectile burster charge.  Accordingly, greater caution should be observed in handling.

The tracer element in these projectiles is loaded in two increments.  First increment is the tracer composition, which is pressed in the after compartment by hydraulic pressure; the second increment is the "starter" mixture, which is pressed in on top of the tracer composition and is more sensitive than the latter.  When the projectile is fired, the heat from the propellent charge ignites the starter which, in turn, sets off the tracer composition.


Identification and Markings

Type ---- Color

H.E. (Tetryl) ---- Light Gray
H.E. (Pentolite) ---- Blue
B.L. & T. ---- Dark Gray Green, with 1/8 inch Yellow band


 




20mm A.P.T. Mk 9

Overall length w/ cap and windshield : 3.051 inches
Overall length w/o cap and windshield: 2.449 inches
Diameter of base: 0.742 inches
Distance base to band: 0.315 inches
Width of band: 0.154 inches
Diameter at bourrelet: 0.784 inches

Weight of loaded projectile: 0.2686 pounds
Charge/Weight ratio: N/A

Cartridge case: Mks 3 and 4
Primer: Mk 31
Tracer: Integral






20mm A/C A.P.T. M95 (New Series)

Overall length w/ cap and windshield : 3.27 inches
Overall length w/o cap and windshield: 2.4 inches
Diameter of base: 0.76 inches
Distance base to band: 0.39 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.78 inches

Weight of loaded projectile: 0.29 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36A1
Tracer: Integral


The tracer is red in color and burns for a period of about 2.25 seconds, equivalent to a range of about 1,400 yards.  This round is superseding the A.P.T. M75 round of the Old Series.

 



20mm A/C Incendiary M96 (New Series)

Overall length w/ nose cap: 3.245 inches
Overall length w/o nose cap: 2.3 inches
Diameter of base: 0.76 inches
Distance base to band: 0.39 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.78 inches

Filling: Incendiary Mixture
Weight of filling: 0.02 pounds
Weight of loaded projectile: 0.27 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36A1
Tracer: N/A


The incendiary mixture fills both the nose cap and the projectile body.  No fuze is required, since the functioning is initiated by impact of the nose with the target.

 

20mm A/C H.E.I. M97 (New Series)

Overall length w/ nose fuze: 3.28 inches
Overall length w/o nose fuze: 2.44 inches
Diameter of base: 0.76 inches
Distance base to band: 0.39 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.78 inches

Filling: Tetryl and Incendiary Mixture
Weight of filling: 0.017 pounds
Weight of loaded projectile: 0.29 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36A1
Tracer: N/A

Fuzes: Nose - M75


This round is superseding the H.E.I. Mk 1 round of the Old Series







20mm A/C Practice M99 (New Series)

Overall length w/ nose fuze: 3.27 inches
Overall length w/o nose fuze: 2.3 inches
Diameter of base: 0.76 inches
Distance base to band: 0.39 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.78 inches

Filling: None
Weight of filling: N/A
Weight of loaded projectile: 0.29 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36A1
Tracer: N/A


This round is superseding the Ball Mk 1 round of the Old Series









20mm A/C H.E.I. Mk 1 (Old Series)

Overall length: 3.22 inches
Diameter of base: 0.77 inches
Distance base to band: 0.5 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.784 inches

Filling: Tetryl and Incendiary Mix
Weight of filling: 0.025 pounds
Weight of loaded projectile: 0.29 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36
Tracer: N/A

Fuzes: No.253 Mk 1


This round is to be superseded by the H.E.I. M97 round of the new ballistically matched series.  The H.E.I. Mk 1 round is to be classified unserviceable by Naval activities as soon as replacement allowances or stocks of the M97 round are received.






20mm A/C Ball Mk 1 (Old Series)

Overall length: 3.31 inches
Diameter of base: 0.77 inches
Distance base to band: 0.5 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.784 inches

Filling: None
Weight of filling: N/A
Weight of loaded projectile: 0.28 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36
Tracer: N/A

 
This round is to be superseded by the practice round M99 of the new ballistically matched series.  The Ball Mk 1 round is to be classified unserviceable by Naval activities as soon as replacement allowances or stocks of the M99 round are received.



 

20mm A/C A.P.T. M75 (Old Series)

Overall length: 3.25 inches
Diameter of base: 0.77 inches
Distance base to band: 0.5 inches
Width of band: 0.203 inches
Diameter at bourrelet: 0.784 inches

Filling: None
Weight of filling: N/A
Weight of loaded projectile: 0.37 pounds
Charge/Weight ratio: N/A

Cartridge case: M21A1
Primer: M36
Tracer: Integral

 
This round is to be superseded by the A.P.T. round M95 of the new ballistically matched series.  The A.P.T. M75 round is to be classified unserviceable by Naval activities as soon as replacement allowances or stocks of the M95 round are received.

Next Time: 40mm Projectiles

American Projectiles and Explosives - 20mm and 40mm Projectiles

American Projectiles and Explosives

Minor Caliber Projectiles




20mm Ammunition

Two types of 20mm weapons are at present in service use in the Navy: the Oerlikon anti-aircraft gun and the Hispano-Suiza aircraft gun.  These types differ widely in construction and functioning; and it is emphasized that the ammunition, though somewhat similar in external appearance, is not interchangeable.




Ammunition for Oerlikon Gun

The Oerlikon gun and its ammunition are of naval manufacture and design.  The ammunition may be distinguished from that designed for the Hispano-Suize gun by the reduced diameter of the extractor lip at the base of the cartridge case.  For identification of the individual types of rounds, the body of the projectile is painted a distinctive color, as follows:

*When the projectile is assembled with "Dark Ignition" tracers, a 1/8-inch bright red band will be painted around it midway between the bourrelet and the rotating band.

The Mark and Mod, manufacturer's initials or symbol, and lot number are stamped around the body of the projectile.


Abbreviations in Minor Calibers

H.E. --- High Explosive
I. --- Incendiary
T. --- Tracer
B.L. --- Blind Loaded
P. --- Plugged
S.D. --- Self-Destructive
D.I. --- Dark Ignition



Ammunition for Hispano-Suiza Gun

This gun and its ammunition are Army-designed but have been adopted as Naval equipment with the installation of the gun on Naval planes.  The ammunition is distinguished from that designed for the Oerlikon gun by the extractor lip on the base of the cartridge, which is the same diameter as the rest of the case.  Two series of ammunition for this gun are in use.  The "Old Series" consists of unmatched rounds, some adapter from British prototype, others designed by the Army.  The "New Series" is a set of ballistically matched rounds designed by the Army to supersede those of the "Old Series".  For identification of the individual types of rounds, the body of the projectile is painted a distinctive color, as follows:

1.1"/75 Ammunition

The body of these projectiles, now obsolete items, were unpainted except for two dots below the fuze, indicating as follows:

Explosive D --- Yellow dot
Tracer --- Red dot

A newer color marking was proposed for the 1.1-inch ammunition.  Some projectiles may be found painted as follows:

H.E.-T.  -- Light Gray with White band
H.E.-T./S.D. -- Dark Green with White band
B.L. and P. -- Red overall
B.L. and T. -- Red overall with White band




40mm Ammunition

These projectiles are identified by distinctively colored bodies, as follows:

The tracer composition is either a red burning mixture in the tracer -- "T" rounds -- or a non-luminous burning compound in the "Self-Destructive" rounds.

"Dark" and "Dark Ignition Tracer": To eliminate the blinding effect on 40mm and 20mm gunners from tracer fire at night, and also to make the origin of tracer fire less distinct, these tracers were developed toward the close of the war.  The dark ignition tracer is invisible until the projectile is 100 to 400 yards from the gun's muzzle, and then it is visible for the rest of its time of flight.  Details of these tracers are described with their appropriate projectile and tracer housing.

Inert Fillers

(For details on explosive payloads, please see earlier updates in the US explosive updates)


Blind Loaded and Plugged (B.L. & P.):  A projectile may be loaded with sand or other inert material and sealed with a solid base plug, or the tracer hole (fuze hole) in a base plug may be blanked off.

Blind Loaded and Tracer (B.L. & T.): These projectiles have an inert load, but a tracer is inserted in the fuze hole of the base plug.

White Phosphorus: An unstable smoke-incendiary agent, white phosphorus ignites when exposed to air and produces dense white smoke.  It also has its incendiary, anti-personnel effect.

Gas: The various types of gas fillings are listed further below.

Color and Markings of new projectiles, 3-inch and larger

Explosive Indicator

Yellow ---- Explosive D
Grey ---- Black Powder
Green ---- TNT
1/2 Grey and 1/2 Green band ---- TNT and Black Powder mix
Red ---- Inert material or empty
Blue ---- Composition A

Time Fuze Stripe

Projectiles having a nose time fuze shall have a 1/4-inch white stripe painted longitudinally from the stationary lug on the fuze two inches aft.

Body Color

Black ---- AP

Slate Grey ---- Common

Green -- AA, HC, and AA Common

Light blue with two white stars ---- Illumination

Aluminum ---- Window

White ---- Shrapnel

Ocean Grey ---- Smoke, Gas, or Incendiary

Red ---- Targer ammunition

V.T. Fuzed

The letters "V.T." 3/4-inch high are stencilled just before the rear edge of the paint indicating the burster charge.

Tracer Band

A white band with four dots 90 degrees apart indicates the color of the tracer.

Spotting Band

The color indicates the color of the spotting charge.

"Window" Mark

This consists of a one-inch high "W" on each side, 180 degrees apart, just abaft the forward bourrelet.

Stenciling on Body

The following information is stenciled between the rotating band and the forward bourrelet on new projectiles:

-Ammunition lot number

-Caliber and type of projectile

-Mark and Mod of projectile

-Type nose fuze (whether MTF, PDF, VTF, Mk 32 and similar types, or Dummy Nose Plug)

-Mark and Mod of fuze

-Lot number of fuze (for Mk 32 and similar types only)

-Mark and Mod of auxiliary detonating fuze

-Mark and Mod of base detonating fuze

-Mark and Mod of tracer 

-Color of tracer

-Mark and Mod of guns in which projectile can be used

-Mark and Mod of "Window" load

-Stamped on rotating band

-Mark and Mod of projectile

-Size and Type of projectile

-Lot number and year of specification

-Inspector's seal and initials

-Sometimes the manufacturer's name is included here

Stamped on base or on base plug

-Mark and Mod, size, and type of projectile

-Lot number, year of specification

-Inspector's seal and initial

-Manufacturer's name

The serial number of the projectile will also be stamped on the base plug on the side of the body, and on the windshield if present.

Chemical Filler Markings

Two green bands, 1/2-inch apart ---- Persistent casualty gas
One green band ---- Non-persistent casualty gas
One red band ---- Harassing gas
One yellow band ---- Smoke
One purple band ---- Incendiary

Also, on projectiles having a chemical filler, there is stenciled the type of chemical, such as SMOKE, INCENDIARY, or GAS, and the symbol or letter designating the particular filler.





Color and Marking of older projectiles, 3-inch and larger


In addition to the explosive filler, body color, spotting specifications, and base and band stamping mentioned above, the older projectiles had the following markings:

Tracer Band: White band with three dots, indicating tracer color, 120 degrees apart.

V.T. Fuzing: One-half inch red band painted one-half inch abaft the nose fuze.


Stenciled on the body

-Size, caliber, Mark and Mod of projectile
-Mark and Mod of fuzes
-Explosive filling and density of loading
-Abbreviated name of loading dept.
-Initials of Chief Inspector
-Date of filling and marking; any changes in filling, fuzing, etc.


Stamped on base

Weights before and after filling.

Next Time: 3-inch Projectiles

German Projectiles - 7.92mm to 30mm Projectiles

German Projectiles





German Projectiles



German Cartridges, S.A.A., 7.92mm

 German 13mm Solothurn

German 15mm Mauser

German 20mm Mauser & Oerlikon Ammunition

H.E Projectile for Tapered Bore Gun, 28.2mm

German Designation: Sprgr. Patr. Pz. B41 (Sprenggranate Patrone Panzerbuchse 41)

Employment: s. Pz B 41 (schweres Panzerbuchse 41)


Dimensions

Overall length (complete round): 8.5 inches
Overall length (projectile): 2.531 inches
Diameter at bourrelet: 1.129 inches
Diameter of body midway: 0.752 inches
Diameter of projectile base: 1.128 inches
Total weight of projectile: 3.1 ounces
 Total weight of bursting charge: 1.8 ounces

Type of filling: PETN/Wax
Tracer present

Overall length (cartridge case): 7.375 inches
Diameter at case neck: 1.175 inches
Diameter at case shoulder: 1.567 inches
Depth of extracting groove: 1.885 inches
Weight of propellant: 5.3 ounces
Type of propellant: Nz. RP (Tubular Nitrocellulose)

Fuze: AZ 5072

Markings: Black overall








A.P. Shot with Core for Tapered Bore Gun, 28.2mm

German Designation: Pzgr. Patr. Pz. B41 (Panzergranate Patrone Panzerbuchse 41)

Employment: s. Pz B 41 (schweres Panzerbuchse 41)


Dimensions

Overall length (complete round): 8.5 inches
Overall length (projectile): 2.531 inches
Diameter at bourrelet: 1.129 inches
Diameter of body midway: 0.752 inches
Diameter of projectile base: 1.128 inches
Total weight of projectile: 4.6 ounces
Length of tungsten carbide core: 1.593 inches
Diameter of tungsten carbide core: 0.43 inches

Type of filling: Tungsten Carbide Core
Tracer present

Overall length (cartridge case): 7.375 inches
Diameter at case neck: 1.175 inches
Diameter at case shoulder: 1.567 inches
Depth of extracting groove: 1.885 inches
Weight of propellant: 5.4 ounces
Type of propellant: Tubular Nitrocellulose

Fuze: None

Markings: Black overall with red band









Inert-Loaded Projectile for Aircraft Cannon, 30mm

German Designation: 3cm

Employment: Mk 103 or Mk 101


Dimensions

Overall length (complete round): 11.719 inches
Overall length w/ fuze (projectile): 5.25 inches
Diameter at bourrelet: 1.187 inches
Width of rotating band: 0.312 inches
Diameter of projectile base: 1.125 inches
Distance from base to band: 0.781 inches

Type of filling: Filled with inert Bituminous composition
Tracer present

Overall length (cartridge case): 7.25 inches
Diameter at case neck: 1.25 inches
Diameter at case shoulder: 1.375 inches
Diameter of rim: 1.5 inches
Type of propellant: Smokeless powder

Fuze: Dummy

Markings: Grey overall, yellow band above rotating band;
Two cannelures below rotating band;
"Wb K2 41" on cartridge case.










A.P. Projectile with Core for Aircraft Cannon, 30mm

German Designation: 3cm Pzgr. 40 (Panzergranate 40)

Employment: Mk 103 Rheinmetall-Borsig


Dimensions

Overall length (complete round): 11.625 inches
Total weight of complete round: 1 pound, 12.5 ounces
Overall length (projectile): 5 inches
Diameter at bourrelet: 1.187 inches
Width of bimetallic rotating band: 0.312 inches
Diameter of projectile base: 1.156 inches
Width of bourrelet: 0.375 inches
Distance from base to band: 0.625 inches
Weight of projectile: 13.5 ounces

Type of filling: Tungsten Carbide Core

Overall length (cartridge case): 7.25 inches
Diameter at case neck: 1.25 inches
Diameter at case shoulder: 1.375 inches
Depth of extracting groove: 1.5 inches
Type of propellant: Smokeless powder


Markings: Painted Black with white tip 1.75 inches long;
"UNT 1c" and date stencilled in white on projectile
"Wb K2 41" on cartridge case.










H.E. Projectile for Aircraft Cannon, 30mm

German Designation: 3cm Sprgr (Sprenggranate)

Employment: Mk 103 Rheinmetall-Borsig


Dimensions

Overall length (complete round): 11.75 inches
Overall length (projectile): 5.375 inches
Diameter at bourrelet: 1.156 inches
Width of rotating band: 0.156 inches
Diameter of projectile base: 1.156 inches
Distance from base to band: 0.875 inches

No tracer present

Overall length (cartridge case): 7.25 inches
Diameter at case neck: 1.25 inches
Diameter at case shoulder: 1.375 inches
Depth of extracting groove: 1.5 inches
Type of propellant: Smokeless powder


Markings: Painted Yellow with white band above rotating band;
black band below screwed-in nose piece.
"Wb K2 41" on cartridge case.


Remarks: This projectile has a hollow recess at its base 0.5 inches in depth.
There is one cannelure below the rotating band.








H.E. Projectile with Tracer for Aircraft Cannon, 30mm

German Designation: 3cm Sprgr L'spur (Sprenggranate Leuchtspur)

Employment: Mk 103 Rheinmetall-Borsig


Dimensions

Overall length (complete round): 11.718 inches
Overall length (projectile): 5.25 inches
Diameter at bourrelet: 1.156 inches
Width of rotating band: 0.312 inches
Diameter of projectile base: 1.125 inches
Distance from base to band: 0.781 inches

Tracer present (Not self-destroying)

Overall length (cartridge case): 7.25 inches
Diameter at case neck: 1.25 inches
Diameter at case shoulder: 1.375 inches
Depth of extracting groove: 1.5 inches
Type of propellant: Smokeless powder

Fuze: AZ 1504

Markings: Painted Yellow; aluminum fuze.
"Wb K2 41" on cartridge case.


Remarks: Two cannelures below the rotating band.










A.P Projectile for Aircraft Cannon, 30mm

German Designation: 3cm Pzgr (Panzergranate)

Employment: Mk 103 Rheinmetall-Borsig


Dimensions

Overall length (complete round): 12.218 inches
Overall length w/ fuze (projectile): 5.656 inches
Overall length w/o fuze (projectile): 5.187 inches
Diameter at bourrelet: 1.187 inches
Width of rotating band: 0.25 inches
Diameter of projectile base: 1.156 inches
Distance from base to band: 0.687 inches

Type of filling: TNT
Tracer present

Overall length (cartridge case): 7.25 inches
Diameter at case neck: 1.25 inches
Diameter at case shoulder: 1.375 inches
Depth of extracting groove: 1.5 inches
Type of propellant: Smokeless powder

Fuze: Base fuze for 3cm Pzgr.

Markings: Painted Black with yellow band above bourrelet;
Red band above rotating band.


Remarks: Two cannelures below the rotating band.

Next Time: 37mm to 42.48mm Projectiles

Imperial Japanese Navy Ammunition - 20mm Projectiles

Imperial Japanese Navy Ammunition

Type 99 20mm Ammunition

 

Naval 20mm ammunition is divided into two classes: Type 99 Mk I and Type 99 Mk II.  The two are distinguished by the fact that the Mk I uses a small-size cartridge case (3.79 in), and the Mk II uses a large-size cartridge case (3.98 in).

Both sizes use the same projectiles and fuzes, but there are a greater number of types and modifications of rounds in the smaller size.


This ammunition is a Japanese copy of the Swiss Oerlikon design.  In addition to rounds of Japanese make, some of Swiss origin have been used by the Japanese.
 

Case  -----  Mk I ------ Mk II
Length ----- 3.79 in ----- 3.98 in
Diameter at base ----- 0.75 in ----- 0.75 in              
Weight (empty) ----- 57 grams ----- 71 grams      
Material ----- Brass ----- Brass  
 

 
The cases are of the reduced-rim type and are crimped to the projectiles by either three or six crimps at the cannelure, and sealed with a clear lacquer. 

 

Propellant:
The propellant from the Japanese-manufactured rounds is graphited, single-base, single perforated, cylindrical, nitrocellulose grains.  The propellant from the Swiss rounds is single-base, graphite-coated, nitrocellulose grains, in the form of flakes.  The Mk I case contains 13.6 grams of propellant and the Mk II case contains 21.4 grams of propellant.
 

Projectiles:
In the case of Japanese manufactured ammunition, the type of projectile is indicated by painting the projectile body a solid color.  Subsequent modifications of the original type are indicated by one or more white bands around the projectile body, thus:
 

Original type: No bands
Modification 1: One 5mm white band
Modification 2: Two 5mm white bands
Modification 3: Three 5mm white bands
Modification 4: One 10mm white band
 

All the Swiss projectiles are painted a solid color without bands.
 

The following dimensions are common to all projectiles:

Distance from rotating band to bourrelet - 1.29 inches
Distance from rotating band to base - 0.36 inch
Diameter of body - 0.77 inch
Diameter at bourrelet - 0.79 inch
Diameter at rotating band - 0.83 inch




20mm High-Explosive Projectile

 
Weight of projectile (fuzed): 4.5 oz
Length of projectile (fuzed): 3.23 inches

Length of complete round:
-Mk I: 5.66 inches
-Mk II: 6.84 inches

Filling: Pentolite (50 percent TNT, 50 percent PETN)
Weight of filling: 0.35 oz

Fuzing:
Japanese: Model 2
Swiss: Model 1

Color and markings:
Japanese: Rust brown overall (modifications indicated by white bands)
Swiss: 1. Yellow overall   2. Dark Brown overall

Remarks:
Ammunition of Swiss manufacture has been found to contain slightly more explosive than the Japanese round.

20mm High-Explosive Incendiary Projectile

Weight of projectile (Fuzed): 4.51 oz
Length of projectile (Fuzed): 3.23 inches

Length of complete round:
-Mk I: 5.66 inches
-Mk II: 6.84 inches

Filling:
-TNT: 0.18 oz
-WP: 0.11 oz
-Incendiary Mixture: 0.04 oz

Fuzing:
-Basic Projectile: Model 1
-Modification I: Model 1
-Modification II: Model 3
-Modification III: Model 2
-Modification IV: Model 3

Colors and markings:
Greenish-Yellow overall, with one or more white bands to indicate modifications.

Remarks:
The body of all projectiles (basic and modifications) is of steel, with one cavity.  The base of the cavity contains TNT, above which is an aluminum cannister containing white phosphorus.  The cannister is surrounded by a graphited, flake nitrocellulose incendiary mixture.  The Model 4 projectile eliminates the TNT and has a longer white phosphorus cannister.

Differences between the basic projectiles and subsequent modifications are principally in the fuzes and slight changes in the shape of the cavity.





20mm High-Explosive Tracer Projectile

 

Weight of projectile (Fuzed): 4.51 oz
Length of projectile (Fuzed): 3.1 inches
 

Length of complete round:
-Mk I: 5.7* inches
-Mk II: 6.88 inches

 

Filling: Pentolite (50 percent TNT, 50 percent PETN)
Weight of filling: 0.18 oz

Fuzing:
-Basic Projectile: Model 1
-Modification I: Model 1
-Modification II: Model 3
-Modification III: Model 2
-Modification IV: Model 3
-Modification V: Two-piece fuze (Japanese designation unknown)

Color and markings:
Red overall (modifications indicated by white bands)

Remarks:
The body of all these projectiles (basic and five modifications) contains two cavities separated by a steel septum.  The upper cavity contains the H.E. filling, while the lower contains the tracer.  The same H.E. filling and tracer mixture are used in all instances.  

Differences between the basic projectile and subsequent modifications are principally in the fuzes and weight of H.E. and tracer filling used.

*The No. Model and Model 1 projectiles are 0.16 inch shorter than the other rounds.



20mm High-Explosive Tracer (Self-Destroying) Projectile

 

Weight of projectile (Fuzed): 4.5 oz

Length of projectile (Fuzed): 3.15 inches

Length of complete round:

-Mk I: 5.58 inches

-Mk II: 6.76 inches

Filling: Pentolite (50 percent TNT, 50 percent PETN)

Weight of filling: 0.15 oz

Fuzing: Model 1

Color and markings:

Japanese: Red overall

Swiss: Black overall

Remarks:

The projectiles are similar to the H.E. tracer types except for their self-destroying feature, which is accomplished by  a hole drilled through the septum of the projectile.  A black-powder train leads from the tracer, through the hole in the septum and the H.E. filling, to the base of the gaine.

20mm Armor-Piercing Incendiary Projectile

 

Weight of projectile: 4.64 oz

Length of projectile: 3.15 inches

Length of complete round:

-Mk I: 5.58 inches

-Mk II: 6.76 inches

Filling: Incendiary mixture

- Nitrocellulose: 77.5%

- Sodium Nitrate: 11.3%

- Aluminum: 11.2%

Weight of filling: 0.12 oz

Fuzing: None

Color and Markings: White overall

Remarks:

The projectile is unfuzed and has a pointed steel body and a soft copper cap soldered to the nose.  The incendiary filling loaded through the base is sealed with a threaded base plug.

Upon impact, the rear end of the projectile ruptures and the heat generated ignites the incendiary filling.

No modifications or similar Swiss ammunition exist.

20mm Tracer Projectile

Weight of projectile: 4.44 oz

Length of projectile: 3.23 inches

Length of complete round:

-Mk I: 5.66 inches

-Mk II: 6.84 inches

 

Filling: Tracer mixutre

Weight of filling: 0.31 oz

 

Fuzing: None

 

Color and Markings: Red overall (modifications indicated by white bands)

 

Remarks:

The projectile is unfuzed; has a blunt nose and a long cavity containing the tracer-element. It is loaded so as to be the first round fired to break the muzzle cover.  It is, therefore, often referred to as a "bag-buster".

In addition to the basic Japanese type, Modifications II and III exist, as well as a similar round of Swiss make.  The weight of tracer constitutes the difference in the Japanese modifications.

20mm Practice Projectile

 

Weight of projectile: 4.45 oz

Length of projectile: 3.23 inches

Length of complete round:

-Mk I: 5.66 inches

-Mk II: 6.84 inches

Filling: None

Fuzing: None

Color and Markings: Black overall

Remarks:

The projectile is unfuzed and has a blunt nose.  It has an empty cavity which is closed at the base with a crimped steel plug.  No modifications exist.

Next Time: 25mm Projectiles

Imperial Japanese Army Ammunition - 20mm Projectiles (Final)

Japanese Explosive Ordnance: Army and Navy Ammunition

Today will be the last post about 20mm Army Projectiles. We start to get into post-1940 projectiles which were used in the Ho-5 cannon seen on many late-war Japanese fighters.

20mm High-Explosive Incendiary Tracer Projectile

Overall Length: 19.52cm
Length of projectile: 11.98cm
Length of case: 12.38cm
Filling: Cyclonite, incendiary composition, tracer composition

Fuzing: Type 100 small instantaneous fuze.

Color and Markings: Black body with red band just abaft bourrelet, green and yellow bands before rotating band. Characters (flexible or fixed machine cannon) stenciled on the body.

Used in: Ho-1 (Flexible) and Ho-3 (Fixed) aircraft cannon.

Remarks:
The projectile is made of steel and has two cavities, a main charge cavity and a tracer cavity, separated by a septum. The main charge cavity contains two pellets, the forward one, fitting around the fuze gaine, is cyclonite while the after one is an incendiary mixture.



Type 100 Mod 2 20mm I.T. (Self-Destroying) Projectile

Overall Length: 20.93cm
Length of projectile: 8.32cm
Filling: Incendiary composition, tracer composition

Fuzing: Type 100 small instantaneous fuze

Color and Markings: Black body with red band just abaft bourrelet, green and yellow bands before rotating band. Characters (Type 100 Mod 2) are stenciled on the body.

Used in: Type 98 anti-aircraft / anti-tank gun

Remarks:
This is the same projectile as the type 100 and type 100 Mod 1 H.E.T. but there is no high explosive other than that used in the gaine.



20mm Armor-Piercing Tracer Projectile

This projectile came in 3 variations: Type 97 anti-tank gun, Ho-1 and Ho-3 aircraft cannons, and Type 98 anti-aircraft and anti-tank gun.

Overall Length: (97) 19.36cm (Ho-) 19.36cm (98) 20.95cm
Length of projectile: (97) 8.01cm (Ho-) 8.09cm (98) 8.01cm
Weight of projectile: (All) 156g
Length of case: (97) 12.38cm (Ho-) 12.38cm (98) 13.97cm
Filling: Tracer composition

Color and Markings:
Hard round (type 100): black body, green and white bands before rotating band.
Medium Round (Type 97) has (type 100) stenciled on the body, black body, green band before rotating band.
Soft round (Type 97 substitute) black overall.

Medium Round Stencil

Used in: Type 97 anti-tank gun, Ho-1 (Flexible) and Ho-3 (Fixed) aircraft cannon, or Type 98 anti-aircraft / anti-tank gun.

Remarks:
This projectile is a solid steel shot with a tracer cavity drilled into the base. This projectile, with different colored tracers and markings is used in three guns. There are three types of rounds differing in grades of hardness of steel.


Ho-5 20mm Ammunition

Excerpt from the Manual: The latest Army 20mm gun developed is the Ho-5 aircraft gun which is of excellent design and represents a considerable improvement over previous Army 20mm aircraft machine guns.

Case properties
Length: 9.48cm
Diameter of base: 2.46cm
Material: Brass
Weight (Empty): 113.5g

Remarks:
The case is of the rimless type and has a slight taper toward the neck.

Propellant: The propellant is 21.4g of graphited smokeless powder in fine cylindrical grains.



Type 2 and Type 2 Modified 20mm H.E.I. Projectile

Overall Length: 14.6cm
Length of projectile: 6.5cm (Fuzed)
Weight of projectile: 77.4g (Fuzed)
Weight of filling:
-Cyclonite (Type 2 Modified): 3.4g
-Cyclonite (Type 2): 0.4g
-Incendiary composition: 3.7g
Filling: Cyclonite and incendiary composition

Fuzing:
-Type 2: Type 2 small instantaneous or Type 2 small instantaneous modified type.
-Type 2 Modified: Type 4 super-detonating fuze.

Color and Markings:
-Type 2: Black overall and, sometimes, yellow band around body.
-Type 2 Modified: projectile is painted silver-gray overall

Remarks:
The difference between the Type 2 and the Type 2 modified is the fuze. The Type 2 projectiles uses a fuze that has an external gaine and thus has less explosive filling than the Type 2 Modified projectile which uses a fuze with the gain built into the fuze body.




Type 4 20mm H.E.I. (Ma 202) Projectile

Overall length: 14.6cm
Length of projectile: 6.6cm
Weight of projectile: 78.2g (fuzed)
Weight of filling:
-P.E.T.N.: 3.2g
-Incendiary composition: 8.7g
Filling: P.E.T.N., and incendiary composition (barium nitrate, aluminium powder, magnesium powder, and wax)

Fuzing: Fuzeless

Color and Markings: Black overall with characters (202)

Remarks:
The projectile is made of steel with a brass nose piece threaded to it. The nose piece is filled with P.E.T.N. and is designed to explode by the crushing action of impact. An incendiary mixture contained in the steel body is separated from the high explosive by a felt pad and a threaded brass disc. This disc has two lead-in holes.



Type 2 20mm Armor-Piercing Tracer Projectile

Overall length: 14.6cm
Length of projectile: 6.35cm
Weight of projectile:
-Soft Round: 112.7g
-Medium Round: 116.7g
-Hard Round: 119.5g
Weight of filling: 7g
Filling: Tracer composition

Color and Markings:
-Soft Round: Black overall
-Medium Round: Black with green band around body.
-Hard Round: Black with a green and a white band around body.

Characters (Type 2) are stenciled on the body

Remarks:
There are three different models of this projectile differing in the grades of hardness of the steel. This difference is indicated by the color markings.


20mm Practice Projectile

Overall length: 14.6cm
Length of projectile: 6.5cm
Weight of projectile: 81g
Filling: None

Color and Markings: Black overall

Remarks:
The projectile approximates the shape of the Type 2 H.E.I. projectile. It is unfilled and closed at the base by a threaded plug.



Next time: 37mm Cannon Projectiles and more!

Imperial Japanese Army Ammunition - 20mm Projectiles (Continued)

Japanese Explosive Ordnance: Army and Navy Ammunition

Back again with more 20mm ammunition for the IJA. We start seeing some Kanji which I hope will be legible in the photos I take, although some are fairly small and low-res. Unfortunately, there's not much I can do aside from reverse-lookups and trying to determine the best/closest approximation.


Here's a few images to illustrate my point.

How many inches?



The drop in quality doesn't help identifying characters



Nor does inverted colors with random blotches of black





Type 98 20mm High Explosive Tracer Projectile

Wait, you did this one last time, right?

Well, apparently this round was used in the Type 97 antitank gun. Yes, it's confusing.

Overall length: 19.45cm
Length of projectile: 6.11cm
Filling: Cyclonite, tracer composition

Fuzing: Type 93 small instantaneous fuze

Color and Markings: Black body with red band just aft of bourrelet, green and yellow bands forward of rotating band. Type 98 is stenciled on the body.

Used in: Type 97 antitank gun

Remarks:
The projectile is made of steel, with two cavities separated by a septum.



Type 100 20mm H.E.T. (Self-Destroying) Projectile

To add even more confusion to the 20mm round category, the Type 100 came in two versions: one for the Type 97 Anti-tank gun, and another for the Type 98 Anti-air/Anti-tank gun. These are marked as (97) and (98), below.

Overall length: (97) 19.36cm (98) 20.83
Length of projectile: (97) 8.21cm (98) 8.21cm
Weight of projectile: (97) 4.7g (98) 4.7g
Filling: Cyclonite, tracer composition

Fuzing: Type 100 experimental projectile used type 93 small instantaneous fuze; other two projectiles use type 100 small instantaneous fuze.

Color and markings: Black body with red band just aft of bourrelet, green and yellow bands forward of rotating band.

Type 100 has the image below stenciled on the body

Type 100 experimental has the image below stenciled on the body

Type 100 Mod 1 has the image below stenciled on the body

Used in: Type 97 anti-tank gun or Type 98 anti-air/anti-tank gun.

Remarks:
The projectile is made of steel with two cavities separated by a septum. Leading through the septum and into the explosive cavity is a black powder lead-in. When the tracer has burned out it will ignite the lead-in which will detonate the explosive filling.

There is an earlier model of this projectile designated Type 100 Experimental which does not have a self-destroying feature. There is also a Type 100 Mod 1 which differs from this projectile in that it is filled with black powder instead of cyclonite.


20mm High Explosive Incendiary Projectile

Overall length: 19.29cm
Length of case: 12.38
Length of projectile: 8.41cm
Weight of projectile: 127g
Filling: Cyclonite, incendiary composition

Fuzing: Type 93 small instantaneous fuze

Color and markings: Black body with red band just abaft bourrelet, yellow band forward of rotating band. The characters (fixed or flexible machine cannon) are stenciled on the body.

Used in: Ho-1 (Flexible) and Ho-3 (Fixed) aircraft cannon.

Remarks:
The projectile is made of steel. It contains two pellets, the forward one surrounding the fuze gaine, is cyclonite while the after pellet is an incendiary mixture.


20mm High-Explosive Incendiary (Ma 201) Projectile

Overall length: 19.29cm
Length of case: 12.38cm
Length of projectile: 8.63cm
Weight of projectile: 109g
Filling: P.E.T.N., incendiary composition

Fuzing: Fuzeless

Color and markings: Black body with red band abaft bourrelet. Characters (201) are stenciled on the body.

Used in: Ho-1 (Flexible) and Ho-3 (Fixed) aircraft cannon

Remarks:
The projectile is made of steel. A brass nose piece filled with P.E.T.N. threads into the incendiary filled projectile. Detonation of the projectile is accomplished by the crushing action of the P.E.T.N. filled nose piece.



Next Time: MORE 20MM!