Carbines with a bayonet lug began to be issued by late 1944. After WWII, many carbines were retrofitted with bayonet lugs. The Marine in the center of this photograph taken while fighting in Korea in September 1950, has an M4 bayonet attached to his M1 carbine.

Initially, the M1 and M1A1 carbines were produced without any capacity to attach bayonets. Soldiers who carried a carbine were generally provided with an M3 knife to supplement their combat readiness. Photographed on Tarawa, Gilbert Islands, in November 1943, this Marine radio operator is armed with an M1 carbine with no provision for a bayonet. 

Initially, the M1 and M1A1 carbines were produced without any capacity to attach bayonets. Soldiers who carried a carbine were generally provided with an M3 knife to supplement their combat readiness. Photographed on Tarawa, Gilbert Islands, in November 1943, this Marine radio operator is armed with an M1 carbine with no provision for a bayonet.

Photographed on Tarawa, Gilbert Islands, in November 1943, this Marine radio operator is armed with an M1 carbine with no provision for a bayonet. 

When German paratroopers and land forces sped over Europe to begin WWII, the U.S. Army Ordnance Department sped up their search for an infantry weapon for rear echelon troops and crew-served weapons that was more accurate than a handgun, lighter than the US M1903 and M1917 rifles, and less expensive than the Thompson submachine gun. Finally, in 1941, the U.S. military adopted the M1 Carbine — but no bayonet for the weapon.

The M1 and M1A1 carbines were produced without any capacity to attach bayonets. The thought was that the carbine’s light barrel could not withstand the rigors of bayonet fighting.

When the need for a bayonet became obvious, the Ordnance Department efforts revolved around developing a combination knife-bayonet. Six knives were tested, five of which were based on designs patterned after the M1918 MkI trench knife. The sixth was a knife with a D-guard handle.

FROM M3 TRENCH KNIFE TO M4 BAYONET

The M4 bayonet (center and right) is a direct descendent of the M3 trench knife (left). Today, collectors look for production variations of this iconic 20th century weapon.

The M4 bayonet (center and right) is a direct descendent of the M3 trench knife (left). Today, collectors look for production variations of this iconic 20th century weapon.

These early prototypes made the new light-weight carbine muzzle heavy which was deemed unsatisfactory. The Ordnance Department shelved the project and focused on creating a new combat knife. Troops who had been issued carbines would have to rely on the newly developed M3 trench knife until a satisfactory bayonet could be developed.

Reports from the field soon revealed that troops were improvising bayonets for their carbines, however. Clearly, they wanted a bayonet that they could attach to their carbines.

With production of the M3 trench knife well underway, the Ordnance Department renewed the quest for a new bayonet in 1943. They developed and field-tested prototype bayonets that they designated the T4, T5, and T6.

The T4 consisted of an M3 knife blade while the T5 and T6 were spike bayonets similar to those designed for the No.4 Lee-Enfield. All three were attached to the carbine via a barrel ring tightened by a wing nut similar to the already developed M8 grenade launcher.

The M3-bladed T4 was the most desirable, but without a handle, none were useful other than as a bayonet. Furthermore, the wing nut was insufficient to securely attach any of the bayonets to the end of the carbine.

Eventually, in 1944, the Ordnance Dept. decided to create a bayonet based on the M3 trench knife which it designated the T8. To create the T8, they removed the pommel of the M3 and replaced it with a single catch latch plate. The standard hilt was ground off in favor of a guard with a muzzle ring.

During field tests, it was found that a second catch was necessary to prevent the bayonet from becoming accidentally detached from the carbine. The Ordnance Dept. told all M3 manufacturers of to stop production immediately.

Finally, on May 10, 1944, the new bayonet (designated the “M4”) was adopted. Full production began in July of the same year. The M4 bayonet was issued with the same M8A1 scabbard used for the M3 trench knife.

BARREL BANDS AND THE M4 BAYONET

There are three distinct types of barrel bands found on M1 carbines. Collectors have dubbed them the “Type 1,” “Type 2,” and “Type 3.” Jesse Harrison’s book on M1 carbines refers to them as the “Type A,” “Type B,” and “Type C.

To accommodate a bayonet, however, the M1 carbine would require a new barrel band. The military designated the new band the T4 (Type 3 in collectors’ parlance). According to Bruce Canfield’s Complete Guide to the M1 Carbine and the M1 Garand, Winchester and Inland were the only manufacturers who produced carbines with the T4 (Type 3) band during WWII.

USING THE BAYONET IN THE FIELD

Photographic evidence suggests that very few M1 carbines capable of accepting M4s were used during WWII. Those that were issued appear to have been used in the Pacific Theater during the Okinawa campaign.

Beginning in September 1944, M4s were issued to troops for use as a combat knife even though their weapon may not have been able to accommodate a bayonet. After WWII, however, most M1 carbines were retrofitted to accept the M4 bayonet.

Several concerns arose after the M4 bayonet was issued to troops in the field. For example, the two pins that held the latch in place and were designed to be driven out of the catch plate via two small holes drilled into the grip for repairs. In use, these pins had a tendency to become lose and fall out. To rectify this, orders were put out to stake the pins in place in February 1945.

Another concern that arose were the cracks that could develop on the guard in the area of the muzzle ring. In 1951, Springfield Armory developed a new guard that was thicker and wider to resolve this issue.

Beginning in 1954, the M4 bayonet received further improvements. Cracking around the muzzle ring was still a problem, so it was widened further.

Like the M3, the leather handle of the M4 was susceptible to mildew and rot. The new production bayonets were made with black plastic grips similar to those seen on the M5/M5A1 bayonets. Unlike the leather grips which were held on by the peen on the pommel of the bayonet, a pair of screws held the new production M4 grips in place. This made maintenance easier in addition to reducing weight when the tang was milled out to allow the screws to pass through to the other side.

“In the 1990s, Camillus produced a commercial version of this bayonet. It differs in that the center of the “M” in Camillus and the “M4” goes all the way to the bottom of the tang. It is smooth-peened, and the “X” is vertical instead of horizontal. The latch plate is painted rather than Parkerized.” — U.S. Knife Bayonets & Scabbards, by Gary Cunningham

WHY RUBBER GRIPS ON SOME M4 BAYONETS?

Periodically, collectors will encounter M4 bayonets with rubber grips similar in appearance to the original leather grips. The countries of Norway, Greece, and South Korea are also known to have manufactured M4 bayonets for military use. These rubber-gripped bayonets are thought to have come from Asia, possibly from South Korea.

M4 Bayonet Production

Aerial Cutlery Company: 91,898
Camillus Cutlery Company: 332,698
W.R. Case & Sons Cutlery Co.: 224,764
Imperial Knife Company: 917,894
Kinfolks, Inc: 119,702
Pal Blade Company: 268,000
Utica Cutlery Company: 515,000

Total Production: 2,469,956

Turner Manufacturing, Imperial Knife Company, Conetta Tool and Die, and Bren-Dan Inc. received the contracts for this run of M4 bayonets which finally ended in 1970. The only known production number from this later period are the 298,691 bayonets Turner Manufacturing turned out in 1954.

[Source: U.S. Knife Bayonets & Scabbards by Gary Cunningham. U.S. Small Arms of World War II by Bruce Canfield shows slightly different production numbers.]

M4 Bayonet Values

M4 Bayonet Values: Pricing is based on eBay auction prices realized, Sep.2, 2020 to Nov. 30, 2020.

M4 Bayonet Values: Pricing is based on eBay auction prices realized, Sep.2, 2020 to Nov. 30, 2020.

The legacy of the M4 bayonet, regardless of origin or variation, lives on to this day. Not only did the M4 become the first successful dual-role bayonet developed by the U.S., by combining the role of a bayonet and combat knife, it set a trend in bayonet design that continues to present day. 

US bayonet length changed before and after the adoption of the M4. From left to right are a Model 1905, 1942 manufactured M1905, M1, M4, M4, and M7.

US bayonet length changed before and after the adoption of the M4. From left to right are a Model 1905, 1942 manufactured M1905, M1, M4, M4, and M7.

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