What makes a rifle a rifle?
September 21st, 2011 at 8:54 pm (Vocabulary)
I recently learned what the term “rifle” means. It turns out that it’s far more interesting than “gun with a long barrel,” which was my previous definition. Instead, it represents a mechanical innovation. The long barrel contains spiraling grooves on its inside, such that the raised parts of the grooves make contact with the bullet and impart spin to it.
“Like throwing a football?” I wondered, and sure enough, wikipedia uses that exact analogy! The spin gives the projectile additional stability and therefore range (and precision targeting).
The term “rifle” comes from the French rifler, a verb that means “to graze or scratch”. The rifles, then, are the spiral grooves or scratches — and the gun originally was called a “rifled gun.”
So a rifle does have a long barrel, to accommodate the spiral grooves and enough time to spin the bullet (>100,000 rpms!). But it’s what’s inside that counts.
Terran said,
September 26, 2011 at 12:34 pm
Exactly! And even short firearms these days are rifled — snub-nosed revolvers, for example, still have rifling. It increases accuracy (and, therefore, effective range) *dramatically* compared to smooth bore. It turns out that there’s a whole bit of algebra in figuring out the right twist rate for rifling. For a “rifle” (i.e., long-bore, high-power firearm), you can get away with a much slower turn rate because the muzzle velocity is typically quite high, compared to a shorter firearm. So that snub-nosed revolver will have a much higher rate of twist, because the bullet is (a) traveling slower, and (b) doesn’t have as much distance to “spin up” as in the longer firearm.
IIRC, there was also something of a tech innovation race in the late eighteenth or early nineteenth century to figure out how to *cut* rifling grooves correctly and consistently. When you think about it, you have this rod of fairly hard steel about 2 or 3 feet long, and you want to cut a *perfectly straight* hole down it, with *perfectly consistent twisted grooves* along the sides of the hole. Not straightforward!
Also, in police/murder mystery novels and media, when they do the “did this bullet come from this gun?” trick, this is what they’re measuring. It turns out that all firearms have slight differences in the lands and grooves pattern produced by their individual rifling (akin to variations in human fingerprints). This is what the investigators are measuring — the marks left on the bullet by the rifling as it traveled down the barrel.
Cameron said,
April 7, 2013 at 1:34 pm
Thanks, Wanted to learn what the definition of a rifle was and learnt lots extra.
Does a modern assault rifle also have grooving/rifling? Also does a modern pistol/handgun have rifling/grooving?