5.56 vs 7.62: A Comparison

Headstamp-to-Headstamp is our series aimed at helping you grok everything ammo.

It’s September of 1970. After a strongly worded letter from President Johnson and six weeks at Paris Island, a fresh recruit finds himself walking down a trail through a dense section of jungle, a newly minted Private in the Marine Corps.

In his hands is the new Colt M16 — derided by some and loved by others in the platoon. Chief among the 5.56 NATO rifle’s dissenters is the platoon sergeant, who has been using the M14, chambered in 7.62 NATO, since the war to end all wars.

The going concern is that the smaller 5.56 round won’t perform at 500-yards or even the 300-yard mark the corps has long-held as a sacred test for long-range shooting. The M16, other hand, has been engineered to deliver effective stopping power and range for the kids of bad-breath distances all too common in the jungles of Vietnam. 

In the bushes just off the trail, a young LASV guerilla stalks with his AK-47 chambered in 7.62×39, listening to this conversation amongst the U.S. troops, before deciding to ruin everyone’s day.

This anecdote, the likes of which played out for nearly a decade in the jungles of Vietnam, gets at the heart of this article; the two of the rounds that defined Cold War firearms development, the 5.56mm NATO and the 7.62×39.

By Michael Crites

Michael Crites is el jefe around here. He has spent more than 30 years shooting, learning about guns, and collecting firearms old and new. He holds his Oregon Concealed Handgun License, and enjoys testing products in the back 40 of his farm.

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