The M4 bayonet was produced in late WWII for the M1 Carbine rifle, and comes in many versions; leather handles, plastic, wood & rubber. Made by Aerial, Camillus, Case, Imperial, Kinfolks, Pal, Utica. This bayonet is very similar in appearance to the M7 bayonet except for the barrel ring difference.
WW2 to 50's
Circa 1944. Early ACC (early) Aerial in a modified M8 BM Co -scabbard.
Imperial M4 in a correct M8A1 BM co scabbard.
w. rubber handle
Possibly South Korean refit for leather handle M4 -bayonets.
w. wooden handle
Arsenal refit for leather handle M4 -bayonets. According by some sources, at Okinawa, late 40's.
Refitted WW2 M4
Camillus (arsenal refit)
Bren-Dan, M7 handles
The M4 bayonet of the second series of production was manufactured by: TMN, CONETTA, IMPERIAL, AND BREN-DAN. The guard is shaped differently. 1954. This bayonet is not an military issue bayonet, but meant for commercial market.