US Grenade Cartridges©

Grenade Cartridges (GC) are not Blanks.  By US standards a blank is loaded with a small amount of fast burning powder which gives that audible "bang", simulating gun fire.  A grenade cartridge is similar in that there is no projectile.  That is where the similarity ends.  Grenade cartridges have a full powder charge and work with pressures about 1/2 of those of standard ammunition.  Unlike a blank, it is not unusual to get 25,000-30,000 pounds per square inch pressure while firing a grenade cartridge with a heavy projectile. 

Unfortunately some of the older designations of similar cartridges used the word "blank".  Also it is disturbing to know that during the postwar period foreign countries had also used that designation for grenade cartridges.  By WWII, Ordnance had the two designations straightened out and never interchanged them again, except once.  On the insistence of the Army Air Forces and a requirement by the Aircraft Radio Laboratory at Wright Field resulted in the "Cartridge, Blank, Caliber .30, T61, Antenna Erecting" and was produced in very small quantities in 1945 (16,500).  

This study is geared strictly toward Grenade Cartridges of WWII and postwar and does not address Blanks.  That is another subject for somebody else.

What is a Grenade Cartridge?  It is the cartridge used to launch anti-tank or anti-personnel grenades, pyrotechnic signals, or chemical agents from a rifle.  Under most circumstances it gave the rifleman or grenadier a very lethal capability; the ability to destroy many of the light and medium armored vehicles and various types of fixed fortifications.

How is it used?  The grenade cartridge provides the propelling charge to launch a heavy projectile as listed in the previous paragraph.  A special adapter is provided for the rifle which gives the projectile a stable launch platform.  The adapter is known as a Grenade Launcher and each launcher is different for each type of firearm.  Once the projectile is on the launcher the grenade cartridge is fired.  The hot gases push the projectile off the launcher, hopefully towards the target.

The Cal. .30 Grenade Cartridge, M3

Before WWII there were various types of cartridges, each for a unique use.  Chemical Blanks, Grenade Cartridges, Pyrotechnic Signal Cartridges, were just a few of those in use before WWII.  As the war approached and newer heavier anti tank grenades were developed the requirement for an improved "all in one" cartridge arose.

This newer cartridge was also encouraged by the then recent testing of the T3 Grenade Launcher (GL) for the 1903 Rifle and newly developed anti-tank rifles grenades. In response Frankfort Arsenal (FA) engineered the Caliber .30 M2 Grenade Cartridge for testing.  It consisted of 5 grains of FFFG black powder and 51 grains of IMR-4676.   The M2 was used as a test standard and was never produced in large quantities.

Soon research and development started at Frankford Arsenal on the M3 with the goals of standardization and high production. The specifications at that time required the cartridge to propel the 20 ounce rifle grenade 165 feet per second, measured 5 1/2 feet from the launcher.  This was accomplished with 5 grains of black powder and approx. 45 grains of IMR-4676.  This specification was briefly assigned the designation M3.  As grenade launchers and projectiles changed, so did the specifications. 

The Caliber .30 M3 Grenade Cartridge was standardized in September of 1941. The final specification for the M3 increased the projectile's required velocity to 180 feet per second at 5 1/2 feet from the launcher.   Mass production started and 40 grains of IMR-4898 was substituted to lower the cost and for ease of loading.  Black powder would remain in the loading throughout the wartime period.

There were constant disagreements inside Frankford Arsenal about the addition of black powder, which was used as a reliable source of ignition.  Since the days shortly after WWI ordnance loaded black powder in all similar cartridges with the concern that since there was no projectile like that with conventional ammunition, powder ignition would be incomplete.  Today many published references note the addition as a booster.  Not so, says Mr. C. Robert Olsen (Bob Olsen), a young engineer at Frankford Arsenal during the war.  Bob Olsen, during this wartime work at Frankford Arsenal attempted to get the black powder removed from M3 GC loadings.  It wasn't until after the war that ordnance would adopt the results of many of the tests he performed.  All the post war loadings of the M3 relied strictly on smokeless powder.  The M6, which Mr. Olsen helped develop, never used black powder during its production. The results of testing and his perseverance convinced FA that the black powder requirement could be eliminated; the smokeless powders would get sufficient ignition without it.  Sometime after the war FA changed the specifications to reflect the elimination of black powder from the M3 loading.

 

US Grenade Cartridge Assortments©

The Grenade Cartridge Assortments were packed in the M13 Can.  Many people refer to these as "Spam Cans" as they resemble the canned food product SPAM.  The M13 can had a "Key Opener" semi-permanently attached to its side.  The key was used for opening the can, very similar to a vacuum packed can of coffee from the 1960's.  The key's slot was inserted over a metallic strip, and as the key was turned the strip cut away the M13's top. 

There has been much speculation as to why so many varieties of Grenade Cartridge Assortments were produced.   With no written documentation being available only an educated guess can be made.  Before going into the reasoning, let's first look at what has been uncovered so far.

For ease of definitions I came up with a numerical description for each assortment.   It is as simple as stating the components in the order as seen on the assortments' cans.   Thus:

                                 

10 Ea - Caliber .30 Grenade Cartridges, M3
6 Ea - Caliber .30 Carbine Grenade Cartridges, M6
5 Ea - Grenade Auxiliary Cartridges, M7

The above assortment 10-6-5 was the only assortment still listed a 1974 Identification Listings for ammunition; the rest were deleted years earlier. My guess is this variety was produced in such large quantities that many still were in the system.   This assortment was by far the most common and can still be found at gun shows.  Several 10-6-5 assortments were packed in each bulk crate of 48 illumination ground signals, including parachute and star cluster.

 

10 Ea - Caliber .30 Grenade Cartridges, M3
6 Ea - Caliber .30 Carbine Grenade Cartridges, M6
0 Ea - Grenade Auxiliary Cartridges, M7

 

10 Ea - Caliber .30 Grenade Cartridges, M3
6 Ea - Caliber .30 Carbine Grenade Cartridges, M6
10 Ea - Grenade Auxiliary Cartridges, M7

The 10-6-10 is the Grand Daddy of all the Grenade Cartridge Assortments.  It contains the most components of all the variations, 26 cartridges. 

 

10 Ea - Caliber .30 Grenade Cartridges, M3
0 Ea - Caliber .30 Carbine Grenade Cartridges, M6
5 Ea - Grenade Auxiliary Cartridges, M7

 

10 Ea - Caliber .30 Grenade Cartridges, M3
0 Ea - Caliber .30 Carbine Grenade Cartridges, M6
10 Ea - Grenade Auxiliary Cartridges, M7

 

The above assortment shows a different format of marking but the same contents as the other 10-0-10.  The painted over reference to the M6 Grenade Cartridges is missing . The above photo courtesy of Ray Gram from Wisconsin.

 

15 Ea - Caliber .30 Grenade Cartridges, M3
0 Ea - Caliber .30 Carbine Grenade Cartridges, M6
0 Each - Grenade Auxiliary Cartridges, M7

Why were there so many varieties?  It appears that the 10-6-5's were first as they were packed with most projectiles.  Most likely each military unit was using certain components in greater quantities than others; often wasting the unused components.  This was due to the different types of weapons issued to units, or the different types of missions assigned to each unit.  The supply system made a variety of Grenade Cartridge Assortments which gave each unit the ability to requisition only those types of cartridges needed for its requirements.  This is just speculation If I am ever able to find supply documents on WWII ammunition I may be able to clear up how the various assortments were stored and issued. 

The individual components of each can is shown below.  The WWII packages consist of a heat sealed package surrounding a light cardboard carton which contained the cartridges.  All components I have seen had either Frankford Arsenal or Lake City markings on the component packaging.

 

The M3 Grenade Cartridge when a component of the various assortments was packed in a small cardboard carton which consisted of 2 rows of 5 cartridges. 

The M6 Grenade Cartridge was packed in both marked and unmarked cartons, 1 row of 6 cartridges.  This specimen is one of the marked cartons.  Many were packed without markings, sealed in heavy wax, and an identification strip buried under the wax on the top flap. I suspect the waxed versions were never packed inside the Grenade Cartridge Assortments.  Most likely they were issued as is.

 

The M7 Auxiliary Cartridges were packed in small cartons of 5 Each.  I have never seen a different packing.

 

 

Fast Forward to the 1960's

10 Ea - Caliber .30 Grenade Cartridges, M3
0 Ea - Caliber .30 Carbine Grenade Cartridges, M6
0 Each - Grenade Auxiliary Cartridges, M7
Repack from 1967, the only such combination I have observed from the Vietnam Era. It makes sense as the others were made obsolete years earlier.

 

 

Finally for the sake of history I have made available drawings of the various Grenade Cartridges.  Please be aware that each of these files is HUGE, so you can view all the information.  Download time will be quite long for those with dial up connections. Each drawing is 800 pixels wide, which will cover your entire computer screen. These drawings are for reference only and are copied here so those with historical interest can keep the information alive.   Do Not Attempt To Manufacture Grenade Cartridges, you can get hurt in the process.

During this project my scanner crashed so the drawings were duplicated by digital camera.  The resulting files are not squared and have a few creases; sorry it could not be done any other way at the time.

M1 Pyrotechnic Signal Cartridge

Caliber .30 M1 Grenade Cartridge

Caliber .30 M3 Grenade Cartridge

Caliber .30 Carbine M6 Grenade Cartridge

M7 Auxiliary Cartridge

Feel free to save these drawings to your computer for reference.  It will save you future download time and help keep my bandwidth low. 

Copyright March 2004