Why are rifles (and other long guns) the length that they are?

Here’s an interesting video, well narrated.

I am good with a pistol.  Very Good, in fact.  I focused on pistol proficiency while preparing informally, and in later formal training for my second trip to Afghanistan.  I decided that my “most likely use case” was being surprised at short range in close quarters, and prepared myself accordingly.  I drilled twice daily throughout my deployment, in a self-designed regimen, which included a fairly obsessive clearing and checking practice.

Anyway, I neglected my long-arm skills as much as I could.  I declined the opportunity to carry both guns.  The rifle would only get in my way in most scenarios, and given the real need to carry two types of ammunition just to support the burden of carrying two types of weapon, the option to carry the rifle “just in case” is not cost-free.  To the contrary, I decided that the cost outweighed the benefit, given that a rifle fight probably meant more of a fight, and that in such a circumstance, I would not be hard-pressed to find a newly-available rifle.

Well, the rifle at my option was a carbine anyway, and it took me some time to learn why it was called a carbine.  Turns out that there are two distinct reasons for calling a rifle a carbine, which I learned from the comment of this video, and upon consideration, it has the ring of truth.

There is a sphoisticated argumrnt for the ideal barrel length based on pressure and mass, and therefore velocity, as well as accuracy, but these wind up being secondary considerations in real-world military situations.  What really matters is the ability to launch lead downrange effectively and swiftly, which has a lot more human factors than the ideal calculations will reveal.

Of note, as he discusses in the last use case, the Colonnier (sp?) is every morsel the length of a long rifle, but take a moment and look at the greatly reduced furniture (the wood, more or less).  Despite the lack of a length distinction, that Colonnier is a much nicer rifle to carry and operate just by the sight of it.

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8 thoughts on “Why are rifles (and other long guns) the length that they are?”

  1. Ian McCollum has done another short video on the endlessly contentious question of whether “carbine” rhymes with “combine” or “machine”.

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  2. Haakon Dahl:
    Of note, as he discusses in the last use case, the Colonnier (sp?) is every morsel the length of a long rifle, but take a moment and look at the greatly reduced furniture (the wood, more or less).

    I believe the rifle he shows at the end is the Berthier fusil Mle 1902 (“rifle, model of 1902”), which was issued to troops in Indochina.  It had a three round clip-loaded magazine and used the same 8 mm ammunition as the Lebel main battle rifle.

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  3. John Walker:

    Haakon Dahl:
    Of note, as he discusses in the last use case, the Colonnier (sp?) is every morsel the length of a long rifle, but take a moment and look at the greatly reduced furniture (the wood, more or less).

    I believe the rifle he shows at the end is the Berthier fusil Mle 1902 (“rifle, model of 1902”), which was issued to troops in Indochina.  It had a three round clip-loaded magazine and used the same 8 mm ammunition as the Lebel main battle rifle.

    Good stuff!  Lest anybody scoff (as I used to) at the supposedly puny 8mm ammo (or 7.62 or 5.56), thinking (say) “Well, that’s not even a 9mm round!”, the advantage of a rifle is primarily that the barrel length give a lot more time for the bang to convert into energy in the projectile, without requiring super-human engineering to keep the gun from blowing up.

    A “puny” round fired from a rifle will hit with a lot more stopping power than a “manly” round from a pistol.

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  4. Haakon Dahl:
    A “puny” round fired from a rifle will hit with a lot more stopping power than a “manly” round from a pistol.

    Indeed—when it comes to muzzle energy, there’s no replacement for barrel length.  The 8 mm Lebel had muzzle energy of 3,751 joules with the 15 gram FMJ bullet.  Today’s 5.56 NATO has around 1,700 to 1,800 joules depending upon bullet and loading, while 7.62×51 NATO is around 3,500 joules.

    By comparison, 9 mm Parabellum has muzzle energy between 450 and 600 joules with an 118 mm barrel, the .45 ACP 450 to 800, and the mighty .44 magnum 1000 to 2000 joules (190 mm barrel).  Pistol barrel length matters, but eventually reaches a plateau where all of the energy from the expanding gas has been delivered to the bullet.  Here is a chart of 9mm muzzle energy for barrel lengths between 2 and 18 inches.

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  5. I tend to think this video kind of has things backward.

    Most military equipment was driven, I would contend, by things like available gunpowder (and attendant cost), projectile weight and ballistic stability (which was well known empirically if not scientifically in the 19th century), and convenience.

    Thus, no cavalry I know of shot on horseback except at close range – except perhaps the Comanche and the original Texas Rangers. “Rifles” then, when carried by a cavalry unit, would need to be of such configuration to allow easy “unholstering” and “reholstering” since the cavalry did not ride openly carrying their rifles but rather in scabbards. Thus a shorter length rifle would be of greater use to a cavalryman as he dismounted to fight and remounted to move. Read of Buford’s first day fight with the Confederates at Gettysburg. His soldiers dismounted and kept a spirited firefight up thanks to Spencer carbines, against Hall’s regular infantry, who ended up having to deploy and fight like a real infantry unit, at which time Buford would withdraw a ways and do it all over again.

    The next piece of technology to consider was the introduction of smokeless powder. Smokeless is several factors greater in power, burn rate, pressure (and lack of obscuring smoke) than black powder. So old rifles that used black shot long barrels when they could because black burns slowly so takes a long time to fully burn up and accelerate a bullet. Hence the long rifles, which we had way back in the Revolutionary War, when the average height of an American was 5’4″. The rifle length was not built to make rank fire, but rank fire was adopted to long rifles as a way of increasing the volume of fire of a ranked infantry unit. But smokeless made aiming more useful and lack of smoke made disclosure of position less likely, and increased power made bullets fly faster. Compare the speed of a .45-110 to a .30-’06. Yet the .45-110 in a Sharps could nail a buffalo a LONG way away, so speed is not the limiting factor of accuracy. Indeed, most well made black rifles are more accurate than smokeless. Back in the 19th century if you got a rifle that did not shoot a MOA or less you took it back as defective. Today the standard rifle does well to shoot 3 MOA.

    With the advent of cartridges, reloading became simpler. With the advent of magazines, reloading became a whole lot simpler and faster. ?Do you realize that Crazy Horse’s Sioux at Little Big Horn were mostly equipped with Henry repeaters while Yellow Hair’s cavalry had Springfield single shot carbines in .45-70. Guess who had the rate of fire advantage. Most Western LEO’s had rifles in carbine length, usually in the same calibre as their pistols – most often .44-40. And with the advent of Maxim’s machine gun, we came to a whole new level of firepower. Look at the standard rifles of the later 19th century. We had the Krag, the Russians had the Mosin-Nagant, and the Germans, forward thinking that they were, had the Mauser 98. But it was the Germans who invented the military .30 calibre rifle cartridge. We followed suit, re-barreling our Springfields to the “new” .30 cal military round, adopted in 1906 – to wit, the .30-’06.

    One of the characteristics of the pre-modern .30 cal military round was that the bullets were somewhat a holdover from the older black days. So the Krag and Russian rifles shot 200 gr bullets, when the new stuff was 150 gr. If you check the rifling of a .30-’06 you will find it is 1-10 twist, NOT the optimal for a 150 gr bullet BUT optimal for a 200 gr bullet. But the military was not going to re-barrel ALL their rifles so they cut and re-chambered their rifles – and the 1-10 twist stayed. When the civilians got examples of the military rifles to copy and produce, they made them the same twist – and to this day a box-stock .30-’06 rifle will have not 1-13 twist but 1-10.

    Anyway, the machine gun made tactics as taught the world over obsolete. (And perhaps we could add the French 75 also as it revolutionized artillery, and it was already THE deadliest weapon on the battlefield.) Units now had to fight more spread out. By WWII German infantry was built around the MG-32 and later MG-42, with the rest of the infantry there to protect the machine gun. We, OTOH, developed the Garand, which while not belt fed, certainly had a far faster rate of fire than the German infantry, and when you added the BAR and the attendant increased mobility we had made our infantry more versatile.

    Modern rifles are hampered by the German General Staff study that claimed that most firefights occurred at <=300 M. That may have been true in Europe (although I would argue even that) but it has shown to not be true in places like the Sandbox and the ‘Stan. Longer shots are definitely useful, and the benefit of the old M-14 has once again shown itself. So the 5.56 mm round has not been useful in any real way other than allowing troops to carry a LOT of ammo, much of which they needed to put down the enemy, especially lately when we “solved” the tumbling effect of early M-16 rounds upon impact. But to go back to Hawk’s original commentary, pistols are not for anything but last ditch self-defense, and even then they are only good because they are convenient. Were they really efficient in taking down an enemy, there would be pistols, not rifles, as the primary arms of armies. But rifles are still the weapon of choice. Talk to any trauma unit and you will quickly find incoming GSW’s that a handgun wounds are not worried about a lot, but the few that are rifles are. Totally different level of energy, even for the relatively anemic 5.56 vs any handgun. If you are looking for the ultimate defensive/offensive weapon for short range fighting, an SBR with an auto switch and a can – preferably in .300 BLK with a 200 gr bullet and just barely subsonic. THAT’s a shootin’ iron!

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  6. For those coming in here without having dived deeply into ballistics or physics, a large part of the revolution due to smokeless powder was a result of the simple equation:

    E = ½mv²

    This says that the energy of a moving object, such as a bullet, expressed in units like joules, is proportional to its mass (say, in grams), and the square of its velocity (say, in metres per second).  Ignore the units: the point is that if you double the mass of the bullet, you only get twice the energy, but if you double its velocity, you get four times the energy.

    With black powder and metallurgy of the era, there was a relatively low limit on the velocity, even with a very long barrel.  The .45-70 black powder cartridge would deliver a muzzle velocity between 500 and 700 metres/second (depending upon load and barrel length).  It had a bullet diameter of .458 inch and a heavy lead projectile of around 26 grams to deliver muzzle energy of 2,370 joules.

    The advent of smokeless power and steel able to handle higher chamber pressure changed the game.  The .30-06 Springfield smokeless power cartridge reduced the bullet diameter to .308 inch (identical to the 7.62 NATO round) and halved its mass to 11.2 grams, but with a muzzle velocity of 850 metres per second, it had a muzzle energy of 3,949 joules—that square of the velocity makes a big difference!

    The smaller and lighter bullet, along with reduction in the diameter and weight of the barrel, meant the infantryman could carry more ammunition.  Before long, smaller calibre, high velocity, smokeless powder ammunition replaced large calibre black powder arms because it was better in every regard, and that little two after and above the “v” in the energy equation explained a lot of it.  The higher velocity of the smokeless powder rounds meant their trajectory was “flatter” (didn’t fall as rapidly with distance), and hence were usable to greater range by riflemen with average marksmanship.

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  7. John Walker’s explanation is absolutely correct. However, while ballistics are one thing, there are other factors that make a weapon useful or not.

    If you hunt any big game in Africa, you find mass is really important. Rhinos, elephants, cape buffalo all have very thick skin. Our bullets are mostly meant to stop inside the first soft-skinned animal they hit. Thus the technology makes them expand easily and well. But for the big game one first has to penetrate the skin. So instead of all the fancy bullets of today, you often shoot brass “solids” – solid brass bullets of significant weight to penetrate into the animal in question.

    Modern police forces pretty much ALL use some version of a hollow point bullet – mostly so you don’t penetrate the perp – and the guy behind him – and the guy behind him. Shoot a FMJ bullet in a Dirty Harry S&W Model 29 and you WILL be penetrating multiple targets, or stopping small rampaging vans.

    In the bad old days of Nam we had ammo that was oversped and the twist rates were incorrect so when they hit something – anything – they proceeded to tumble. If it was an enemy soldier, it made ugly wounds (against the Hague Convention), but often it only hit a twig or vine in the jungle – and ricocheted off to where ever. Compare that to some of the NVA units that might have an old fashioned BAR in .30-’06. Those would act like a chain saw and cut the jungle down leaving no where you could hide.

    Another component is BC or ballistic coefficient. Small fast rounds (like the 5.56) would lose their speed relatively quickly and when they went through transition they would wobble way off aim. The NATO 7.62×51, OTOH, kept it’s trajectory relatively well through transition so was more likely to hit the target. (The 5.56 round was 55 gr initially, then 62; the 7.62 NATO round was 149 gr.) The development of the Barrett .50 cal rifle (4-500 gr bullet) was not meant to be a sniping rifle but a long range competition rifle. Its heavy bullet made it relatively immune to wind effects (at least a LOT less than .308’s) so better able to hit accurately targets out to 1500 yds. That also happens to define a good sniping rifle, but that was not Barrett’s intent.

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