# Big-Ass Gatling Gun? **URL:** \ **Category:** Factual Questions\ **Created:** [June 16, 2014, 3:20am UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877 "2014-06-16T03:20:41Z")\ **Posts on this page:** 13\ **Page:** 2
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 17, 2014, 10:14pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/21 "2014-06-17T22:14:35Z")
Why is caliber the size of the bore for a rifle, and length of the barrel divided by the bore in naval guns? ---
**Author:** ![mlees](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@mlees](https://boards.straightdope.com/u/mlees)\ **Post date:** [June 17, 2014, 10:25pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/22 "2014-06-17T22:25:14Z")
> [@carnivorousplant](#): > > Why is caliber the size of the bore for a rifle, and length of the barrel divided by the bore in naval guns? > **[Caliber (artillery)](https://en.wikipedia.org/wiki/Caliber_(artillery))** > > In artillery, caliber or calibre\[nb 1\] is the internal diameter of a gun barrel, or, by extension, a relative measure of the barrel length. > Rifled barrels introduce ambiguity to measurement of caliber. A rifled bore consists of alternating grooves and lands. The distance across the bore from groove to groove is greater than the distance from land to land. Projectiles fired from rifled barrels must be of the full groove-to-groove diameter to be effectively rotated by the rifling, but the caliber ... “Barrel length”, third paragraph, I hope, helps explain why: > [@](#): > > For naval rifles, the initial change was to actual bore, thus facilitating the manufacture of standard projectiles. They then began to measure the effective length (and therefore range) of the weapon in calibers. These were (and are) a measure of the standardized bore of the barrel versus the rifled bore of the barrel. In other words, a 12/45 is 12"X45= the length of the rifled bore of that gun in inches. This explains the differences in both peneration and long range performance of various naval rifles over the years. In addition to the possible improvements in overall performance (i.e. muzzle velocity and striking force), the increase in barrel length also allowed, in some circumstances, an increase in projectile size [weight] as well. ---
**Author:** ![gazpacho](https://avatars.discourse-cdn.com/v4/letter/g/6f9a4e/32.png) [@gazpacho](https://boards.straightdope.com/u/gazpacho)\ **Post date:** [June 17, 2014, 10:57pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/23 "2014-06-17T22:57:08Z")
> [@Sage\_Rat](#): > > I thought a railgun was like a very precise maglev device, which accelerates a round very quickly, while arc welding is electrocuting the hell out of a piece of metal so it melts? A rail gun works by passing a lot of current through the projectile as it goes down the rails. There is a lot of wear on the rails due to the high current from the rail through the projectile. The rails are basically being melted at the point it is contacting the projectile much like arc welding. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 18, 2014, 12:46am UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/24 "2014-06-18T00:46:49Z")
> [@mlees](#): > > [Caliber (artillery) - Wikipedia](http://en.wikipedia.org/wiki/Caliber_(artillery)) > > “Barrel length”, third paragraph, I hope, helps explain why: Sure, but why use a term that means something else with rifles and pistols? Probably begun by the Royal Navy, where a sloop is not a sloop if commanded by a post Captain…or however it goes. 🙂 ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 18, 2014, 1:06pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/25 "2014-06-18T13:06:36Z")
> [@carnivorousplant](#): > > What the hell do the French have to shoot at with four inch shells? No idea. And I only mentioned the French navy because that was among the first results of a quik’n’dirty search for large-caliber auto cannon. P.S.: such guns chamber rounds and extract spent casings automatically but are still dependent on human loaders to keep the feed racks full. So a qualification on “automatic”. ---
**Author:** ![Dissonance](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dissonance](https://boards.straightdope.com/u/Dissonance)\ **Post date:** [June 18, 2014, 2:45pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/26 "2014-06-18T14:45:40Z")
> [@Enola\_Straight](#): > > A larger calibered plane-mounted version that kills tanks: > [Fairchild Republic A-10 Thunderbolt II - Wikipedia](http://en.wikipedia.org/wiki/Fairchild_Republic_A-10_Thunderbolt_II#Proposed_retirement) > [GAU-8 Avenger - Wikipedia](http://en.wikipedia.org/wiki/GAU-8_Avenger) Just to note, the 30mm GAU-8/A Avenger was selected by the Dutch as the weapon to be used in the [Goalkeeper CIWS](http://en.wikipedia.org/wiki/Goalkeeper_CIWS). It’s never been fired in anger, but it kills missiles too. [Youtube of HNLMS Johan de Witt (L801) Goalkeeper CIWS firing](http://www.youtube.com/watch?v=8EHp7EtjLXk). [Cheesy promotional video for the Goalkeeper, but it does have footage of a Goalkeeper making a hard kill on first a single Exocet, then two Exocets launched 5 seconds apart](http://www.youtube.com/watch?v=eZBFSGzRyV4). ---
**Author:** ![busterpickle](https://avatars.discourse-cdn.com/v4/letter/b/258eb7/32.png) [@busterpickle](https://boards.straightdope.com/u/busterpickle)\ **Post date:** [June 18, 2014, 4:04pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/27 "2014-06-18T16:04:59Z")
> [@gazpacho](#): > > A rail gun works by passing a lot of current through the projectile as it goes down the rails. There is a lot of wear on the rails due to the high current from the rail through the projectile. The rails are basically being melted at the point it is contacting the projectile much like arc welding. Kinda how it works. [A rail gun has a series of electromagnets that are basically pulsed in sequence to accelerate the projectile](http://en.wikipedia.org/wiki/Railgun). The heat is caused by both the energy that has to be dissipated by the electromagnets and the friction of the projectile along the rail. The projectile is obviously interacting with the magnetic field but it in itself does not create the field to which propels it. Just a little nitpick… ---
**Author:** ![AndrewL](https://avatars.discourse-cdn.com/v4/letter/a/3d9bf3/32.png) [@AndrewL](https://boards.straightdope.com/u/AndrewL)\ **Post date:** [June 18, 2014, 4:34pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/28 "2014-06-18T16:34:24Z")
> [@electronbee](#): > > Kinda how it works. [A rail gun has a series of electromagnets that are basically pulsed in sequence to accelerate the projectile](http://en.wikipedia.org/wiki/Railgun). The heat is caused by both the energy that has to be dissipated by the electromagnets and the friction of the projectile along the rail. The projectile is obviously interacting with the magnetic field but it in itself does not create the field to which propels it. You’re thinking of a coil gun. As the link you yourself provided shows, in a rail gun the projectile itself does form part of the circuit and helps create the magnetic field. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [June 18, 2014, 6:06pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/29 "2014-06-18T18:06:15Z")
> [@carnivorousplant](#): > > What the hell do the French have to shoot at with four inch shells? Greenpeace ships, I imagine. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [June 18, 2014, 7:20pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/30 "2014-06-18T19:20:02Z")
> [@md2000](#): > > Greenpeace ships, I imagine. 🙂 ---
**Author:** ![Little\_Pig](https://avatars.discourse-cdn.com/v4/letter/l/c57346/32.png) [@Little\_Pig](https://boards.straightdope.com/u/Little_Pig)\ **Post date:** [June 20, 2014, 7:08pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/31 "2014-06-20T19:08:16Z")
> [@bob\_2](#): > > Interesting video: [http://www.youtube.com/watch?v=NEmgSpJK9qQ](http://www.youtube.com/watch?v=NEmgSpJK9qQ) Christ! ---
**Author:** ![slowlearner](https://avatars.discourse-cdn.com/v4/letter/s/a88e57/32.png) [@slowlearner](https://boards.straightdope.com/u/slowlearner)\ **Post date:** [June 21, 2014, 12:14am UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/32 "2014-06-21T00:14:25Z")
Because the F-35 could only carry enough GAU-8 ammo for a couple short bursts they’re going to mount a smaller Euro designed gun that actually packs a bigger punch, ammo design now is toward high tech and small size, it’s pretty amazing stuff. The US Army has dropped plans for an MRSI artillery system that was pretty awesome. ---
**Author:** ![Corry\_El](https://avatars.discourse-cdn.com/v4/letter/c/ecae2f/32.png) [@Corry\_El](https://boards.straightdope.com/u/Corry_El)\ **Post date:** [June 21, 2014, 4:19pm UTC](https://boards.straightdope.com/t/big-ass-gatling-gun/690877/33 "2014-06-21T16:19:10Z")
> [@Enola\_Straight](#): > > Is there an upper limit to the size of caliber you can make these guns? Hotchkiss made revolving barrel cannon similar in concept to the Gatling, in the late 19th century, mainly for naval applications. The largest common caliber was 3 pounder, ie. 47mm. I’m not sure if any larger prototype was ever produced but the 1 pdr (37mm) especially and 3 pdr revolver cannons were common on warships of various navies for anti-torpedo boat defense (meaning the steam torpedo boats of that era). Those were relatively low power cartridges though for their caliber compared to for example modern GAU-8 30mm. The Russians have also used a 30mm Gatling type gun, the GSh-6-30, in a/c and anti-ship missile defense applications since the 1970’s. [Previous page](https://boards.straightdope.com/t/big-ass-gatling-gun/690877.md?page=1)