Here we see a rundown of the standard bayonet fare for U.S. military rifles from the early 20th Century through the early days of the Vietnam conflict.
From top to bottom: an M1905 sword bayonet with a 16-inch blade on the M1903 Springfield rifle, an M1 bayonet on an M1 Garand, a chopped down bayonet (10-inch blade) made from the legacy M1905 pigsticker redesignated M1905E1 on an M1 Garand, and finally an M4 bayonet on M1 Carbine.
The M4 is very interesting in the respect that it originally wasn’t suppose to exist, and then went on to be both widely used and extensively cloned.
Initially, the M1 Carbine did not accept a bayonet. However, beginning in June 1944, the front band included a bayonet lug. Most earlier carbines were subsequently retrofitted with the bayonet-lug front band. Most U.S.-made M4 bayonets were produced by W. R. Case & Sons Cutlery Co., Turner Manufacturing Co, Imperial Knife Co., Conetta Manufacturing Co, and Bren-Dan Manufacturing Co. using the M8/8A1 sheath, and ran into the early 1960s at least.
Early models used the leather washer handles while post-WWII production shifted to hard rubber or plastic grips. Standard blade length on military spec models was 6.5-inches, overall is 11.5-inches. The M4 bayonet blade even went on to form the pointy end of a later Korean-era M1 Garand bayonet, the M5A1, which replaced both the M1905E1 and M1 bayonet.
The M4 model I just picked up is a Kiffe made in Japan, which would obviously make it a Post-WWII variant.
Though the company was founded in New York in 1875 by Herman H. Kiffe and remained in operation through the 1960s, they contracted their M4 bayos to unknown Japanese makers in the 1950s.
Not meant for military contracts (at least from the U.S.) these were popular with new civilian buyers of surplus M1 Carbines which were widely available for a song at the time. These new bayonets sold for $3 at the time via mail order– about $23 in 2017 greenbacks, which is a deal both then and now.
1967 ad for Kiffe, note the “M8 Bayonet” in the top right with “self-sharpening plastic sheaths” (!)
Overall length is 11.25-inches, while weight is 8.6-ounces, in each case without the scabbard.
The blade is marked simply “Kiffe Japan” as is the hilt.
While not a true martial bayonet, it is beautiful and this specimen is very minty– no doubt because it was purchased during the Atomic-era as a keepsake to complete a privately owned M1, rather than for field use. At 50~ years old, it looks great and I think it will hold up for another 50 with no problem.