Talk:Rifling

error?
"and in high velocity bullets an excessive twist can cause bullets to literally tear themselves apart under the centrifugal force"

This cannot be correct. The forward linear velocity of the projectile has nothing to do with the centrifugal force needed to keep it together as it spins. —Preceding unsigned comment added by 24.60.154.52 (talk) 19:42, 5 November 2006

Indeed excessive velocities for a given twist can make the bullet fly apart due to centrifugal force. This was a common problem with the .220 Swift if the bullet was driven too fast. The result was a blue-ish streak downrange as the bullet flew apart.

If you do some calculations, starting with a 3000 foot per second bullet in a 12 inch twist rifled barrel. You will find that in this instance, the RPM is 180,000 RPM. Three thousand feet (or revolutions) per second time 60 seconds in a minute = 180,000 RPM.

Increase the twist rate to one turn in ten inches and you can multiply the 180,000 RPM by 12/10.

Increase the velocity to 3200 feet per second and you can multiply the 180,000 RPM by 3200/3000.

It is not at all difficolt to see that the bullets may approach a quarter of a million RPM in some modern rifles.

The first time I did these calculations I thought my calculator was broken.

--230RN —Preceding unsigned comment added by 66.53.13.142 (talk) 05:52, 10 July 2007

Flechettes?
The last sentence in the top paragraph: "Extremely long projectiles such as flechettes may require high twist rates; these projectiles must be inherently stable, and are often fired from a smoothbore barrel." Maybe I'm misunderstanding, but this sentence makes no sense to me. It's been in the article since the Aug 2008 rewrite. 1. It's awkward to talk about twist rates as being "high" or "low". "Long" or "short" work for the barrel length per rotation. "Fast" or "slow" work for actual RPMs. "High" and "low" are misleading, since shorter rates are higher rpms, but "lower" twist rates. 2. Best I can work out is that flechettes want a short twist rate, and thus a very low RPM. Then it goes on to say they're often fired out of smoothbore barrels. So why are they mentioned at all? Smoothbore barrels are barrels that AREN'T rifled. I'm not an expert. Am I wrong about this? LordQwert (talk) 05:26, 7 April 2018 (UTC)


 * "Inherently stable" refers to aerodynamic stability without any spin. Since flechettes are so narrow, they would need to spin very quickly to be stabilized via angular momentum. In practice, this rate of spin is impossible to achieve, so usually flechettes just use fins for stabilization. If you're using fins anyway, you might as well use a smoothbore barrel to improve muzzle velocities.


 * This rationale is rarely applied to small arms; it is widely applied to modern tank guns, since nowadays these are optimized to fire APFSDS rounds (basically a single, large, saboted flechette). Note that APDS rounds (somewhat stubbier spin-stabilized sabot rounds) also exist. In any case, I don't think either of these can really be called "flechettes". Multiple (fin-stabilized) flechettes are also fired from smoothbore barrels in the form of exotic shotgun shells.


 * Rabbitflyer (talk) 20:26, 28 May 2020 (UTC)

Suggested edit
because the ".303" refers to the bore diameter in inches (bullet is .312), while the ".308" refers to the bullet diameter in inches (7.92 mm and 7.82 mm, respectively).

because the ".303" (7.70 mm) refers to the bore diameter in inches (bullet is .312) (7.92 mm), while the ".308" (7.82 mm) refers to the bullet diameter in inches.

Also: I’m wondering if “bullet diameter” is the same as “groove diameter” for the .308, and others. MBG02 (talk) 17:59, 14 August 2018 (UTC)

History
By the magic of Wikipedia, "rifling is said to have originated in Augsburg around the year 1498" (from the not particularily high-quality source) became "Barrel rifling was invented in Augsburg, Germany in 1498".

Subsequent claims (including about spin-stabilized arrows) lack citations altogether.

This entire section needs some rework. Cheers ✦  hugarheimur 20:01, 20 June 2019 (UTC)