.308 Winchester vs. 7.62x51mm NATO


When I acquired a Springfield Armory M1A, I was eager to put ammunition in it and then shoot the ammunition at targets downrange; this is, after all, what guns are for. However, this eagerness was tempered by nagging, ill-formed doubts about what kind of ammunition to feed this fine piece of applied ballistics: .308 Winchester or 7.62x51mm NATO? Rifles in .308 are capable of hurling a bullet through 24 inches of oak from two football fields away, so it behooves one to be sure he's got the right kind of ammo chambered before gently nuzzling his face against the rear of the receiver. For that reason, I decided to find out the difference (if any) between .308 Winchester and 7.62x51mm NATO ammunition.

Finding an answer turned out to be no problem at all; in fact, I found three completely different answers within the first thirty minutes of internet searches. Truly, there is a bounty of information online! Unfortunately, a great deal of this information is contradictory, much of the rest is incomplete, and next to none of it is backed up by anything resembling an official or reliable source. As much as I love trusting random people on the internet, one has to draw the line somewhere.

To cut a long and boring story short, persistant research finally produced the answers I sought. More importantly, these answers came with enough documentation to convince me that they are correct. In the interest of saving others the effort, I've summarized the results here.

By way of disclaimer, all data in this article are provided merely to help you verify for yourself which ammo is safe to use in your gun. No assertions are made or implied as to its correctness or your safety as a result of following these guidelines, so if you have any doubts you should probably consult someone who carries the appropriate type of liability insurance. I'm not a ballistician, mechanical engineer, or metallurgist; in fact, I don't even have any interesting letters after my name. My only degree is a Bachelor of Science, which is abbreviated "BS". Treat all information printed here accordingly.

The Rules

With that out of the way, here are the rules I personally follow when it comes to 7.62x51mm NATO and .308 Winchester:

  1. Never use .308 Winchester in a rifle chambered for 7.62x51mm NATO.
  2. Check the length of all 7.62x51mm cartridges before using them in a .308 Winchester chamber.

Each of the listings above is a link you can click on for an explanation of why I think it's a good rule to follow. If these justifications strike you as incorrect or, worse yet, dangerous, then check the Frequently Asked Questions section. Still not satisfied? Send an email to hidi.projects@gmail.com.

Thanks for visiting, and be safe.