Description
105mm T81E28 HEP Projectile – 1953 Marked
This 105mm T81E28 HEP projectile is identified by a steel body stamp bearing the year 1953. Its model belongs to the development series that led to the M327 high explosive plastic howitzer projectile. The stamped year places this example in the early Cold War, making it a useful addition to a collection focused on U.S. artillery development and ammunition markings.
Identification and Features
The identifying stamp sits above the driving band. It records the caliber, HEP designation, T81E28 model, lot marking, and year. The YCC manufacturer symbol is listed in Defense Department directories for Chamberlain Manufacturing Corporation of Waterloo, Iowa. The steel stamp and yellow painted lettering provide two distinct groups of identification details.
- Caliber: 105mm
- Stamped designation: HEP T81E28
- Steel stamp: "LOTYCC2-5-1953 105MM HEP T81E28"
- Stamped year: 1953
- Manufacturer symbol: YCC
Function and Contents
HEP means high explosive plastic. In the original service design, "plastic" described the pliable explosive filling, not the projectile's body material. Its blast was intended to break fragments from the inner face of armor, an effect called spalling. The historical M327 had a steel body with a short nose, flat base, and rotating band. Live rounds used an M91-series base fuze; tracer versions were designated HEP-T.
Product History
American interest in HEP ammunition grew in 1947 after British work on squash-head shells. The Army approved the T81 project in October 1948, and early rounds were tested at Aberdeen Proving Ground in 1950. Successive designs addressed shell strength, shape, and performance against armor. After troop tests in the second half of 1955, the Continental Army Command recommended adoption of T81E28. A December 1957 Ordnance report records its approval and designation as M327 in April 1957. That report also states that large-scale procurement was on hold while a competing high explosive antitank, or HEAT, design was evaluated.
Documented Applications
Army data sheets list M327 applications with the M2A1/M2A2 cannons in M101/M101A1 towed howitzers, the M137 in the M102, the M49 in the M52/M52A1, and the M103 in the M108. The latter two are self-propelled howitzers. These are documented applications of the later standardized ammunition family. A 1971 Army firing-table status list also includes M327 HEP under the M101A1, showing that the round remained part of the Army's documented ammunition support well after its initial development.
Equipment History
The M2A1 howitzer entered production in 1940 and became the U.S. Army's main field artillery weapon during World War II. Rock Island Arsenal made its carriage and recoil equipment. The weapon family later received the M101 designation and continued in American combat service through Vietnam. During the 1960s, the lighter M102 reflected a growing need to move artillery by helicopter. Its prototypes appeared in 1962, production began in 1964, and it began replacing M101 weapons in Vietnam in 1966. This shift connected established 105mm ammunition families with equipment built for more mobile units.
Weapon-System Background
The 105mm howitzer system used a broad range of ammunition, including high explosive, smoke, and illumination rounds. Army data sheets give M327 both antitank and antipersonnel roles. The earlier M67 HEAT shell had served as a howitzer antitank round since 1942; the M327 followed with the squash-head approach. The howitzer remained a field artillery weapon used to support ground troops, with specialized ammunition giving it several roles beyond its regular high explosive fire missions.
History of Use
The M327 family also appears in a later chapter of the Vietnam War. An Air Force history records approval for a trial of tracer-equipped M327 HEP ammunition in the AC-130E PAVE AEGIS gunship on May 26, 1972. Seventh Air Force restricted its use to tactical emergencies under its direction. By May–June 1978, the Army's Field Artillery Journal reported that M327 was no longer in production and that the XM622 HEAT round was intended to replace it. These records document the ammunition family's later trials and replacement planning; they do not establish a combat history for this particular body.
Ideal For
Best suited to collections focused on U.S. artillery development, the T81 series, and the early Cold War. The stamped development model and differing painted identification give collectors two marking groups to study. It can also serve as a reference piece alongside period ammunition manuals or a display showing the changes between experimental and standardized projectile designations.
- U.S. artillery ammunition collections
- T81 and M327 development studies
- Early Cold War displays
- Manufacturer and lot-marking research
- Historical ammunition identification exhibits
Approx length 16", Approx width 5", Approx height 5", Approx weight 23.5lbs.
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