A while back James Hogan mentioned one of the biggest pitched battles of ‘gun culture’, the battle over the ‘best caliber’. It’s taken me a bit to get to but I thought it was a good opportunity to illustrate a point I often make about decision making.
This battle has actually been raging for hundreds of years; even as far back as Washington’s army. In those days the weapon of the common soldier was not a rifle but a musket. It was a smooth bore weapon which fired a large projectile that fit loosely into its muzzle. This loose fit was to facilitate more rapid loading. The rifles of the day required a much tighter fit in the bore and therefore could only be reloaded at a fraction of the pace of muskets.
Washington’s army was predominantly armed with muskets but he did have a few companies of riflemen. And so the battle between slow firing but accurate rifles with their small fast projectile and fast firing muskets with their large slow projectile was born. Muskets and muzzle loaders have long since been retired as weapons of war, but the small fast – big slow caliber debate has raged on.
These days, the debate has centered around the 5.56x45 cartridge, currently being used in the M16 class of weapons, and the 7.62x51 cartridge, put to use in a wide variety of specialist weapons. It was only fairly recently that the US Army made the decision to switch to the smaller cartridge. The M14 which precede the M16 as the weapon of choice used the 7.62 cartridge. (Commonly referred to as a .308, a 7.62 Nato, or more broadly as a “30 caliber”) The weapon of choice before that was the M1 Garand which fired an even bigger 30 caliber round, the 30.06.
But after studying the behavior of each bullet and the kind of wounds it would inflict at various ranges, the Army decided that the benefits of the smaller 5.56 cartridge outweighed its weaknesses, and adopted it as the standard. A portion of gun nuts have lamented the decision ever since.
There is an element of gun culture that thinks bigger is always better, even though this is obviously not the case. They ignore the fact that for the Army, caliber selection is the product of compromises. There pros and cons to every decision, and the Army makes it’s choices based not on what would be best for gun nuts, but for the population at large. The average soldier is just that… average. So they need to select a weapon and cartridge which suits that person.
Both the 7.62 Nato, and the 5.56x45 cartridge have strengths and weaknesses, and it’s important to consider all of them. For the purposes of the discussion I’ve broken them down a bit here:
Weight:
The 7.62 cartridge is much heavier than the 5.56 so soldiers can carry more of the latter. Most people will concede this argument, but there is another issue. A rifle designed for the much higher energy of the 7.62 needs to be heavier than one designed for the 5.56. The difference could be made up with modern materials, but then recoil would make ‘average’ accuracy suffer.
Operating on the assumption that the only way a soldier gets ammo into the field is if he carries it, the advantage in this are has to go to the 5.56. Of course, the 22lr is even lighter still and no one thinks we should go with that.
So the truth is that actual cartridge weight might be a tie-breaking issue, but unless the 5.56 can be shown to meet the other requirements, then it’s moot.
Average Accuracy (sub 400 yards):
Modern military firearms are astoundingly accurate, as is the average military ball ammunition. When delivered from rifles of equivalent tolerance, there should be no effective difference in the inherent accuracy of a 7.62x51 and a 5.56x45 cartridge. But just because the equipment is equal doesn’t mean everything is.
The fact is, the 7.62 delivers much higher recoil than the 5.56. That fact alone means that when a sample of ‘average’ soldiers is taken, they will deliver greater accuracy with a 5.56 than with a 7.62. I personally don’t find the recoil from a 7.62 rifle to be particularly prohibitive. But I am not ‘average’. I have years of experience and have fired tens of thousands of rounds with rifles of various calibers. Like most ‘gun nuts’, over time I’ve become more resistant to recoil than most people with less experience.
But my personal preference shouldn’t be a determining factor as much as the ‘average’ experience of a population of soldiers with limited training. And I think the lighter recoil does affect accuracy for your ‘average’ soldier.
Inherent accuracy advantage: None. Effective accuracy advantage: 5.56.
Average Accuracy (over 400 yards):
The simple fact is, even when armed with a weapon designed for great distances, your ‘average’ soldier can’t hit anything beyond 400 yards without a little luck. Accuracy at those ranges requires far more training than your average soldier will ever receive. It will remain the domain of experts and since that’s so, they will also be more capable of coping with the higher recoil of the 7.62 cartridge.
But even beyond that, the small bullet of the 5.56 makes it minimally effective at longer ranges because it won’t retain enough energy to be lethal.
At longer ranges the 7.62 has a clear advantage.
Wound Severity:
The reason the 5.56 has done so well in this area is because of a trick of ballistics. The typical bullet from a 5.56 cartridge is cylindrical. It requires a very fast ‘spin rate’ to stabilize it, and that makes it slightly unstable. So when it strikes a target it begins to yaw, meaning it spins end over end (or something like it) making for a ghastly and hellish wound.
The 7.62 on the other hand delivers more of a shock and will sometimes take a larger mass of flesh with it as it exits. But it often exits, and it takes a large amount of its energy with it. At closer ranges its more likely to make a small entry hole and a small exit hole than the 5.56.
This particular area has been and continues to be heavily studied and widely disputed. For instance as a 7.62 bullet slows down at longer ranges, it becomes more likely to act like a 5.56 bullet, making it more lethal at longer ranges than close up. Also, the 7.62 bullet is large enough and has enough energy so that it can be fired through light obstructions and still kill whoever is on the other side. The 5.56 has been particularly deficient in that area.
So the question becomes one of deciding which problem you’re trying to solve. Since combat involves many of these scenarios in varying proportions, it’s tough to make the call for a clear advantage. Gun nuts tend to lean on the 7.62 because of the ‘bigger is always better’ argument, but having read reams of data on the topic, I personally am unconvinced.
I’d have to call this one a draw.
Time to Proficiency:
How quickly a soldier can learn to be effective with a weapon is a consideration important to the army, but totally unconsidered at the sport rifle range. But with a much lighter recoil, it’s tough for me to imagine that the 5.56 doesn’t outpace the 7.62 in terms of the practice it takes to become proficient with it. A lot of this will depend on the rifle of course, they should be equivalent. But lighter shoving is absolutely easier.
Training Time: Advantage 5.56
This clearly isn’t going to end this debate. The fact is, both calibers are tools suited to specific tasks. A claw hammer, and a sledge hammer are both hammers, but they should not be used for equivalent things. So it is too with the story of the 5.56 and the 7.62. This is one of those debates where you get lots of proclamations and little evidence.
“I think the X.XX is better – end of story!” You’ll read lines like that all over the hunting and gun boards. Me, I’m not so devoted to one or the other. My AR15 is my most accurate rifle at the moment, but I would never take it deer hunting. I’d use a tool suited to solve the problem I’ve got. But if the only problem I have is punching holes in paper, I’m probably going with the 5.56.
For the military though, it's a question of balancing strengths and weaknesses. "As small as can still be effective", seems to be the way they've decided to go. To present, I think that philosophy is being continued.
