This paper discusses the role that cost played in post-War U.S. bayonet design, in light of recently-discovered documentation of U.S. Government bayonet procurements during 1953 and 1954. Lack of documentation around post-War bayonet procurement left researchers to focus primarily on observable differences to explain design changes. For example: the M1 bayonet was too large, too heavy, and used too much steel. Deterioration observed on original design M4 bayonet leather grips was undesirable.

While all of these observations are valid, recently-discovered evidence shows that cost was the compelling driver for adoption of the M5 bayonet in 1953 and M4 Second Production bayonet in 1954. The 1950s design philosophy based in frugality governed U.S. bayonet procurement for the next 30 years. While adoption of the M9 bayonet in 1986 represented a deviation, 1950s frugality still remains. Over 235,000 M7 bayonets have been produced since 1986, some as recently as 2020.

M1 Bayonet—1953 Cost $6.08

The M1 bayonet is constructed around a single forging. Final M1 bayonet production occurred in 1953 at Utica Cutlery Co. Cunningham illustrates an example in the original packaging, showing Utica Cutlery Co’s. contract DA-19-058-ORD-7440. He indicates that the contract was for 75,000 bayonets.[1] Recently-discovered documentation shows the March 1953 award of a $458,000 contract to Utica Cutlery Co. for “Bayonets.”[2] A 1954, Ordnance Department directive to Springfield Armory to accept an overrun of 2,549 additional M1 bayonets from Utica has a handwritten margin note indicating a unit cost of “$6.08 each.”[3]

Figure 1: U.S. M1 bayonet, shown without grips to illustrate the forged construction. (author’s collection)

M5 Bayonet—1954 Cost $1.65

The M5 bayonet was based on a patented design by Michael Mirando, one of Imperial Knife Co’s. owners.[4] Cunningham indicates that J & D Tool Co. had a M5 bayonet contract in 1954 for 57,540 bayonets.[5] I located an image of the packaging from this contract, showing the contract number DA-19-058-ORD-7889. Recently-discovered documentation shows the December 1954 award of a $94,863 contract to J & D Tool Co. for “bayonet knives” (computes to $1.65 per bayonet).[6]

In addition to being smaller, lighter, and using less steel, an essential feature of the M5 bayonet is that it is almost entirely fabricated from stampings. This appears to be a significant contributor to the drastically-reduced production cost.

Figure 2: U.S. M5 bayonet, shown without grips to illustrate the stamped construction. (author’s collection)

M4 Bayonet (Original-Design)—1953 Cost $2.82

Final production of the original-design M4 bayonet occurred in 1953 at Camillus Cutlery Co. Cunningham indicates that Camillus Cutlery Co’s. contract was DA-19-058-ORD-7479.[7] Recently-discovered documentation shows the April 1953 award of a $468,676 contract to Camillus Cutlery Co. for 166,098 “Bayonet knife M4” (computes to $2.82 per bayonet).[8]

Figure 3: U.S. M4 bayonet (original-design) with stacked leather grip. (author’s collection)

M4 Second Production Bayonet—1954 Cost $1.96

Cunningham indicates that Turner Manufacturing Co. was awarded the first M4 Second Production contract in 1954.[9] However, Imperial Knife Co’s M4 Second Production contract, DA-19-058-ORD-7882, actually precedes Turner’s (DA-19-058-ORD-7886). Recently-discovered documentation shows the July 1954 award of a $87,388 contract to Imperial Knife Co. for 44,586 “Bayonet knife, M4” (computes to $1.96 per bayonet).[10]

Figure 4: U.S. M4 Second Production bayonet from the 1954 Imperial contract. (author’s collection)

The plastic grip contributed to reduced production cost in two ways: first, through use of lower-cost materials; and, secondly though lower labor cost. The stacked-leather grip required more-costly skilled labor to assemble, where plastic grips could be assembled using unskilled labor.

Figure 5: M4 Second Production bayonet grip assembly operation at Turner Manufacturing Co. ca. 1955 (Photograph by Max Tharpe, copyrighted image reproduced with permission from Iredell County Public Library, Max Tharpe Photograph Collection, folder titled:  Turner Manufacturing Company)

Lack of government documentation around M4 Second Production design specifications leaves some uncertainty around another cost-saving innovation that evidence suggests also played a part:  the sintered latch plate.

The original M4 latch plate was machined from bar stock or steel forgings. Intricate machining of the rectangular hole, T-slot, and elliptical outer shape was costly and time-consuming.[11] In 1944, a Boston firm, Isthmian Metals Inc., submitted lower-cost latch plates to the Army for evaluation. These were made by sintering (compressing powdered metal).[12] The sintered latch plate required only four simple machining operations: milling the two latch slots, drilling the cross hole (for the internal latch spring), and broaching the tips (upper prongs of the T-slot) to final tolerance.[13]

The Army completed testing and found Isthmian’s sintered latch plates to be satisfactory, but the War’s end stopped bayonet production.[14]

Beginning in November 1954, just four months after Imperial Knife Co. was awarded the first M4 Second Production contract, detailed technical articles authored by Isthmian Metals Co. Vice President, John W. Young, appeared in metals industry trade publications describing their manufacture of M4 bayonet latch plates from powdered metal.[15]

Figure 6: Illustration of the Isthmian sintered latch plate from one of Young’s technical articles published in 1955.

The Imperial M4 Second Production bayonet latch plate has a distinctive Circle-I marking that appears molded-in, rather than stamped like the SP marking on the M4 Original-Design latch plate. Note the absence of any tool marks and rounded edges on the Imperial M4 Second Production latch plate vs. the M4 Original-Design latch plate, where tool marks and crisp edges from machining are evident.

Figure 7: Comparison of the original-design M4 and 1954 Imperial M4 latch plates. (Author’s Collection)

While some uncertainty remains, it appears that use of sintered latch plates likely carried forward through subsequent production of M4 and M7 bayonets. Nearly all of these bayonets’ latch plates exhibit what appears to be a hardness-testing dimple. Why? 1944–45 Army testing revealed a distinct “sweet-spot” on the hardness scale for optimal strength of the sintered latch plate.[16]