Description
81mm M84A1 Time Fuze
Item Overview
The 81mm M84A1 time fuze is a U.S. military component associated with illuminating mortar ammunition. This inert example brings a recognizable part of Cold War ordnance design to a collection, with a history tied to nighttime battlefield lighting and infantry mortar support.
Identification and Features
The 81mm designation refers to the caliber of the mortar ammunition that carried this fuze. Military references document the following features and original service identifiers for the M84A1.
- Designation: M84A1 time fuze.
- Type: Selectable-time fuze with a pyrotechnic timing system.
- Construction: Brass head and body with a ribbed adjustment ring.
- Original timing range: Up to 50 seconds.
- Historical NSN: 1390-00-471-8665.
- Assembly drawing number: 9232784.
Original Function
In service, the M84A1 controlled when an illuminating cartridge released its flare. Its timing system activated an expelling charge that freed the flare and parachute from the projectile. The burning flare then descended beneath the parachute, lighting the ground below. This gave mortar units a way to support observation during darkness.
Documented Ammunition and Weapon Applications
The M84A1 is documented on the M301A3 81mm illuminating cartridge, which Army data lists as standard classified in 1968. That cartridge was used with the M1, M29, M29A1, and M252 mortars. In military supply, the fuze was issued already assembled with the cartridge, making this separate component useful for studying the ammunition’s design.
Product History
The M84A1 developed from the earlier M84 time fuze. It kept the same general form while introducing a tungsten-compound timing train and doubling the earlier model’s maximum timing range. Army ammunition data lists the M84/M84A1 family as standard classified in 1965, placing its development in the Cold War period.
Parent Equipment History
The M29 mortar family followed the earlier M1 in U.S. service during the 1950s. The later M29A1 improved the weapon’s durability through a chrome-plated bore. In 1987, the M252 began replacing M29-series mortars. Developed from the British L16 design, the M252 increased range and supported light infantry, airborne, and air assault units.
Weapon-System Background
The associated 81mm mortars were crew-served weapons built around a smoothbore tube, bipod, baseplate, and sight. Their high-angle flight path allowed ammunition to reach areas beyond intervening terrain. High explosive, smoke, and illuminating cartridges gave the same mortar several support roles, with each ammunition type carrying components suited to its purpose.
History of Use
The 1980 military fuze catalog lists both the U.S. Army and Marine Corps as M84A1 users. Its applications span earlier M1 and M29A1 equipment and the later M252 system. The 2008 mortar manual still documents the M252 using M301A3 ammunition with the M84A1 fuze, showing the design’s continued place in military illumination missions decades after its development.
Condition
This M84A1 fuze is inert and intended for historical collecting, study, and display. It is offered as an individual ordnance component.
Ideal For
The M84A1 fits collections focused on U.S. mortar ammunition, military lighting systems, and the development of time fuzes.
- U.S. Army and Marine Corps ordnance collections.
- 81mm mortar ammunition displays.
- Educational exhibits explaining illuminating ammunition.
- Reference collections organized by military fuze model.
Approx length 4", Approx width 3", Approx height 3", Approx weight 1.8lbs.
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