Prior to the introduction of the Grenade Carrier Vest ammunition for the M79 Grenade Launcher was routinely carried in the 6-round cotton bandoleers it was issued in. However, M79 gunners in Vietnam found that the bandoleers had a tendency to get snagged in the jungle and that one-handed extraction of a single round was difficult.
In an effort to solve these problems a Special Forces Sergeant, in coordination with a Natick Labs representative in Vietnam, fabricated a prototype vest that was successfully evaluated by various units. The vest was made from nylon netting to minimize heat stress and featured 6 pockets (2 on each side of the front and 1 each side of the back) that could each accommodate 3 grenades. Each of the 18 rounds was held in place by a Velcro fastener. Following a directive from Army Material Command, Natick Labs procured 6,687 vests for U.S. forces and all were shipped to Vietnam between May and June 1966.1
As a result of the recommendations made by the Army Concept Team In Vietnam (ACTIV) in September 1967, Natick Labs redesigned the grenade carrier vest. The improved version boasted a capacity of 24 rounds, each of which was held in an individual pocket that was closed by a snap fastener. The body of the vest was made from OG-106 7ΒΌ-ounce nylon duck with raschel knit nylon mesh over the shoulders and back to give increased ventilation. A snap fastener was added to the top and bottom of the front Velcro closure and a strap with quick-operating buckle allowed the back to be adjusted.2
The improved vest, which was designed to be worn over the flak jacket and suspenders, was approved for procurement in January 1968 and was issued in small and large sizes.1. Support To United States Army In Vietnam - Clothing & Equipment (United States Army Material Command Feb 1967)
2. Support To United States Army In Vietnam - Clothing & Organic Materials Vol II (United States Army Material Command Aug 1968)