Why Did The U.S. Military Switch From 7.62x51mm To 5.56x45mm Cartridges?
BY Herschel Smith
4 years, 11 months ago
Ultimately, the decision to shift from 7.62x51mm ammunition to 5.56x45mm came down to simple arithmetic. The smaller rounds weighed less, allowing troops to carry more ammunition into the fight. They also created less recoil, making it easier to level the weapon back onto the target between rounds and making automatic fire easier to manage. Tests showed that troops equipped with smaller 5.56mm rounds could engage targets more efficiently and effectively than those firing larger, heavier bullets.
As they say in Marine Corps rifle teams, the goal is to locate, close with, and destroy the enemy — and the 5.56mm NATO round made troops better at doing precisely that.
I include this not to start another caliber war, but to link up the PDF document, “Rifle Squad Armed With Armed With A Light Weight High Velocity Rifle.”
I had never seen that before and thought readers might find it interesting.
On December 23, 2019 at 6:43 am, Old Bill said:
The decision has come in for a lot of criticism. I’ve leveled some of it myself. But if you look at the specific conditions and requirements the US military was trying to meet at the time, it makes much more sense.
Remember this was done during the Cold War; our most serious challenge was not an insurgent war, but stopping hoards of Communists from overwhelming Europe. Logistics were almost all on the Communist’s side: shear numbers, direct land supply routes, etc… The issue is not just individual cartridge lethality, nor the individual soldier’s load, but also getting enough ammo across the atlantic merely to shoot each enemy once. Given that the cartridge in question was lethal -enough- to either kill or incapacitate, the smaller, lighter, less expensive 5.56×45 has a major logistic effect in our favor.
None (or very little) of that pertains to the individual gun owner or militia member of today. Our logistics and purpose is different, with different requirements. So, if we want to understand the decision to go with the 5.56×45, then we have to look at the requirements that drove that decision, not our current requirements.
I didn’t like the decision when I was in uniform, but it was the right decision for the times. Having seen what “volume of fire” does to ammo supply at the pointy end, it begins to make sense. Also, the history, and losses, of the Red Ball Express should be remembered and heeded.
On December 23, 2019 at 9:07 am, Drake said:
I’ve read the history and don’t think it was a considered decision at all. The Brit .280 would have been a logical and far better choice if the tests in the 50’s hadn’t been totally rigged. Then the Air Force starts buying a lightweight survival rifle, which made sense, and the CEO of GM decides to issue it to front-line troops – which made no sense.
Feedback from troops and actual field commanders like David Hackworth was completely ignored and a really poor rifle was rushed into an already screwed up war.
On December 23, 2019 at 9:12 am, Sanders said:
I still prefer the 7.62×51 or .308 Winchester. Just the other day, I confirmed zero on the M14 at 200, 400 and 500 yards with a ragged hole from each group using Hornady Black. My milsurp ammo doesn’t give me that kind of accuracy, though.
I shot enough 7.62×51 when I was in the Army to know what it will do out to 1,500 meters with iron sights, so it is what I am most comfortable with.
However; that doesn’t mean I hate any other caliber. I shoot more 5.56 because it is cheaper and it is fun to shoot.
What I’ve been saying for years, not that I have a bit of influence with anyone, is that the military needs to go with a more powerful round than the 5.56, but doesn’t need to go as powerful as the 7.62. I used to be an advocate for the .243, but the military seems to be looking pretty seriously at the 6.8, which doesn’t seem to be too bad. I have to research it some more, especially since my wife’s uncle got an AR in that caliber and wants me to load up some ammo for him.
On December 24, 2019 at 4:30 am, Old Bill said:
I prefer the 7.62×51 too. That’s why for my own personal weapon I have a DPMS G2, but MY requirements don’t include supplying a war in Europe. But I also have a 5.56×45; because that’s going to be one of the most common rounds available if things get spicy.
Drake, I think what you say is largely true, but it’s not mutually exclusive with what I said. Army acquisitions is NOTHING if not political; all you mentioned could have reared it’s head within a process whose aim was what I said.