Using a mid-length gas system on an M4A1 carbine extends the life of the weapon system and increases the weapon’s performance over a carbine-length gas system, a study found.
The M14 was the standard infantry rifle for all Army and Marine units that deployed to Vietnam in 1965, but Defense Secretary Robert McNamara ended procurement in 1964, selecting the M16 as a replacement. By 1970, only a handful of M14s remained in Vietnam.