One of the quickest ways to get into an argument at the range is to ask your fellow shooters how .308 Win differs from 7.62x51mm NATO. The responses you’ll get will be across the board, with some insisting that they aren’t different at all, others arguing that they’re wildly different and more neutral parties admitting, in resignation, that they might be different.

The truth is, everyone would be right in some ways, and wrong in others.

But before you start knocking each other over the head with your break barrels, let’s explore the similarities that these two share. To best understand the situation, let’s do a bit of time traveling to the past.

The History of 7.62 NATO vs. .308 Winchester

Throughout the late-Forties and early-Fifties, military rocket surgeons endeavored to improve the efficacy of the M1 Garand and the .30-06 cartridge it used. The most obvious contender that was suited for higher capacity box mags was the newly-modified .300 Savage called the T65.

A rimless bottlenecked rifle cartridge, the T65 was the result of a years-long test program, one that found the T65 to demonstrate power equal to that of the classic .30-06. It could fire 147 grain rounds at 2,750 FPS.

This cartridge laid the groundwork for what the 7.62 NATO would eventually become and is widely understood to be the first iteration of the cartridge. It had a 47mm case and carried steel jacket lead core 150 grain Flat Base bullets.

It was this cartridge that found favor among the military for emergency operations. But, as always, the commercial market was a cash cow begging to graze and Winchester saw the opportunity to make big bucks off a civilian model.

In no time at all (1952, to be exact), they had introduced the .308 Winchester. Here’s where the argument can be made that they aren’t different since the .308 Win was specifically designed to be a civilian variant of the 7.62x51mm NATO, even hitting the market two years before the NATO adoption of the 7.62.