# What's the difference between a rifle (or gun) and a cannon? **URL:** \ **Category:** Factual Questions\ **Created:** [June 30, 2005, 1:55pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510 "2005-06-30T13:55:52Z")\ **Posts on this page:** 18\ **Page:** 2
**Author:** ![SlyFrog](https://avatars.discourse-cdn.com/v4/letter/s/a3d4f5/32.png) [@SlyFrog](https://boards.straightdope.com/u/SlyFrog)\ **Post date:** [July 1, 2005, 5:07pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/21 "2005-07-01T17:07:01Z")
Interestingly, in the U.S. Civil War I believe that some guns were referred to as “rifled cannons” (such as the Parrott) versus guns like the Napoleon (which I think was a “smooth bored cannon.” I think that anything higher than a small arm was effectively a form of artillery, which could be cannon (effectively direct fire), howitzers, or mortars (indirect fire). ---
**Author:** ![Perderabo](https://avatars.discourse-cdn.com/v4/letter/p/a183cd/32.png) [@Perderabo](https://boards.straightdope.com/u/Perderabo)\ **Post date:** [July 1, 2005, 5:13pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/22 "2005-07-01T17:13:01Z")
Look at the picture in [this link](http://www.brook.edu/FP/projects/nucwcost/davyc.htm). The text says: "The Davy Crockett consisted of an XM-388 projectile launched from either a 120-millimeter (XM-28) or 155-millimeter (XM-29) recoilless rifle (the 120 millimeter version is shown above). " Why is that thing called a “recoiless rifle”. There isn’t even a barrel involved. ---
**Author:** ![Mk\_VII](https://avatars.discourse-cdn.com/v4/letter/m/5f9b8f/32.png) [@Mk\_VII](https://boards.straightdope.com/u/Mk_VII)\ **Post date:** [July 1, 2005, 5:39pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/23 "2005-07-01T17:39:13Z")
the barrel is the shiny thing in the top picture. It’s an open-ended tube, all the blast goes out through the vent at the back. These tubes were usually rifled. ---
**Author:** ![Perderabo](https://avatars.discourse-cdn.com/v4/letter/p/a183cd/32.png) [@Perderabo](https://boards.straightdope.com/u/Perderabo)\ **Post date:** [July 1, 2005, 5:47pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/24 "2005-07-01T17:47:29Z")
Well, then that big thing at the front has fins. Those fins look like they would resist spinning. Do I guess it doesn’t spin, and a center rod holding it in the barrel does spin? Not that I’d argue with some dude wielding one of those. He wants to call it a rifle? Fine by me! ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [July 1, 2005, 10:12pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/25 "2005-07-01T22:12:33Z")
> [@tomndebb](#): > > The actual combat MiGs were armed (as noted on the page) with a pair of 23mm cannon plus a 37mm cannon that combined to tear the hell out of anything that got in its sights Dammit I _knew_ that from an old Airfix model my Dad and I made years ago when I was a kid. Its still hanging in my room in Polish Air Cavalry livery, complete with the three mentioned guns at the nose of the aircraft. > [@tomndebb](#): > > The F-86 was actually under-armed (until later models) with six .50 caliber (or 12.7mm) machine guns, which made killing the heavily armored MiG a hassle throughout the Korean war And dammit I knew that as well :smack: From the UK History channel, another few viewings and I’ll know what happened at Leyte Gulf in WWII too. See kids, this is what happens when you don’t apply your accumulated knowledge :rolleyes: ---
**Author:** ![Raguleader](https://avatars.discourse-cdn.com/v4/letter/r/258eb7/32.png) [@Raguleader](https://boards.straightdope.com/u/Raguleader)\ **Post date:** [July 2, 2005, 4:21am UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/26 "2005-07-02T04:21:48Z")
> [@tomndebb](#): > > This sentence is misleading. The machine gun that the article mentions was mounted on a trainer. The actual combat MiGs were armed (as noted on the page) with a pair of 23mm cannon plus a 37mm cannon that combined to tear the hell out of anything that got in its sights. The F-86 was actually under-armed (until later models) with six .50 caliber (or 12.7mm) machine guns, which made killing the heavily armored MiG a hassle throughout the Korean war. (Interestingly, the Navy version, the FJ _Fury_, was armed with four 20mm cannon from the outset.) Yaknow, this is the first time I’ve heard the MiG-15 refered to as “Heavily armored”. My understanding of the plane was that it was a lightly armored, heavily armed, very agile interceptor. But yeah, the .50 cal did lack the punch of the 20’s later used. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [July 2, 2005, 5:10am UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/27 "2005-07-02T05:10:42Z")
> [@Hypno-Toad](#): > > The round has fins to impart spin instead of rifling in the barrel Where do the fins go? Does the barrel have slots, or do they flip out as the round leaves the barrel or are they at the back inside the diameter of the round like a mortar? ---
**Author:** ![David\_Simmons](https://avatars.discourse-cdn.com/v4/letter/d/9de053/32.png) [@David\_Simmons](https://boards.straightdope.com/u/David_Simmons)\ **Post date:** [July 2, 2005, 5:23am UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/28 "2005-07-02T05:23:50Z")
> [@Princhester](#): > > Where do the fins go? Does the barrel have slots, or do they flip out as the round leaves the barrel or are they at the back inside the diameter of the round like a mortar? The round is mounted on a sabot that closely fits and seals the bore against loss of pressure. The diameter of the sabot is slightly larger than that of the projectile When the round and the sabot exit the muzzle, the sabot drops away since it has high aerodynamic drag and the projectile proceeds on its own with the fins imparting spin. ---
**Author:** ![Cerowyn](https://avatars.discourse-cdn.com/v4/letter/c/82dd89/32.png) [@Cerowyn](https://boards.straightdope.com/u/Cerowyn)\ **Post date:** [July 2, 2005, 5:29am UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/29 "2005-07-02T05:29:36Z")
> [@Raguleader](#): > > Hmm… I assumed that all the original M1s had been refit to M1A1 or M1A2 standards. So if I was correct in that assumption, then the M1s _used_ a rifled cannon, but _use_ a smoothbore now. > > Was my assumption incorrectly made? If so, then on behalf of me I’d like to say “Oops.” Of the 3,273 original M1s, a total of 998 are being upgraded to A2 specifications, in lieu of new production. (The most recent program was scheduled to end last year, but I don’t know what the status of it is.) Excluding Abrams produced for foreign countries, 5,017 M1A1s were produced for the US Army and USMC. Just 77 tanks were built as M1A2s from the ground up, but as mentioned above nearly a thousand have been converted from M1s. Incidently, the new SEP (system enhancement package) was added to 240 M1A2s, and I believe it will eventually be rolled out to all A2s. Next on the horizon for the Abrams is said to be a new engine, as the current one has been out of production since 1992. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [July 2, 2005, 12:58pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/30 "2005-07-02T12:58:46Z")
> [@Hypno-Toad](#): > > 20mm seems to be the arbitrary point at which a weapon is called a cannon. I don’t know if there is a technical difference or if everyone simply agreed on it for classification purposes. 20mm is the point where you can practically start loading rounds with explosives. > [@Padeye](#): > > I’ve never heard reference to a chain gun outside of a video game but **Hypno-Toad** ’s description of a rotary gun is right on. They are often called Gatling guns but that term is only correctly applied to the Civil war era hand cranked version. Some rotary guns are chain guns, but the terms are not synonymous. There are chain guns that have one barrel, such as on the Bradley and Apache. And as far as the term “gatling gun” - it’s come to refer to any multibarreled automatic weapon, even if the original didn’t have that exact functionality. > [@Perderabo](#): > > Why is that thing called a “recoiless rifle”. There isn’t even a barrel involved. Recoilless rifles are essentially tubes that launch rockets. This is to distinguish them from explosive-launched projectiles. ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [July 2, 2005, 5:27pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/31 "2005-07-02T17:27:06Z")
> [@Raguleader](#): > > Yaknow, this is the first time I’ve heard the MiG-15 refered to as “Heavily armored”. My understanding of the plane was that it was a lightly armored, heavily armed, very agile interceptor. But yeah, the .50 cal did lack the punch of the 20’s later used. It seems you are right and my aging memory had confused “toughness” (construction integrity such as that demonstrated by the B-17) with armor:[Soviet pilots regarded the MiG-15 as much sturdier than the F-86, and it seems evident that the MiG-15 featured the famous “tractor toughness” of the best Soviet gear. Pilots warmly called it the “samolyot-soldaht (soldier aircraft)”. Many pilots insisted insist that MiG-15s that were claimed as “kills” often made it back home and lived to fight on.](http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=124) ---
**Author:** ![Padeye](https://avatars.discourse-cdn.com/v4/letter/p/a9a28c/32.png) [@Padeye](https://boards.straightdope.com/u/Padeye)\ **Post date:** [July 2, 2005, 5:58pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/32 "2005-07-02T17:58:15Z")
> [@SenorBeef](#): > > Some rotary guns are chain guns, but the terms are not synonymous. There are chain guns that have one barrel, such as on the Bradley and Apache. Fair enough but can you give me a definition for chain gun? ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [July 2, 2005, 7:18pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/33 "2005-07-02T19:18:07Z")
> [@Padeye](#): > > Fair enough but can you give me a definition for chain gun? [From Wikipedia](http://en.wikipedia.org/wiki/Chain_gun) > [@](#): > > Rather than being dependent upon recoil to actuate the system, a chain gun instead depends on an external motor. The motor drives the chain, which slides the bolt assembly back and forth to load, fire, extract and eject cartridges. ---
**Author:** ![Raguleader](https://avatars.discourse-cdn.com/v4/letter/r/258eb7/32.png) [@Raguleader](https://boards.straightdope.com/u/Raguleader)\ **Post date:** [July 2, 2005, 8:12pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/34 "2005-07-02T20:12:20Z")
> [@tomndebb](#): > > It seems you are right and my aging memory had confused “toughness” (construction integrity such as that demonstrated by the B-17) with armor:[Soviet pilots regarded the MiG-15 as much sturdier than the F-86, and it seems evident that the MiG-15 featured the famous “tractor toughness” of the best Soviet gear. Pilots warmly called it the “samolyot-soldaht (soldier aircraft)”. Many pilots insisted insist that MiG-15s that were claimed as “kills” often made it back home and lived to fight on.](http://www.militaryfactory.com/aircraft/detail.asp?aircraft_id=124) Heh, on the subject of B-17s and armor, I read in The Mighty Eighth (by Gerald Astor, IIRC) that the only armor plating on the B-17Gs was located under the seats of the flight crew “…because they knew what they wanted to protect.” And on the subject of cannon rounds vs. bullets, I seem to recall reading somewhere that they had .50 calibre machine gun rounds with explosive tips. I suppose they probably weren’t very practical to produce or use (don’t know how much use the amoutn of explosive you could fit in something that small would do vs. a solid slug) Also, don’t modern 20mm cannon rounds used on fighter planes tend to be solid slugs? A friend told me they rely on their insanely high refire rate to basically shred a target to pieces rather than try to blow them up. ---
**Author:** ![Ficer67](https://avatars.discourse-cdn.com/v4/letter/f/c57346/32.png) [@Ficer67](https://boards.straightdope.com/u/Ficer67)\ **Post date:** [July 3, 2005, 6:32pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/35 "2005-07-03T18:32:14Z")
Another possible difference is the propellant charge. The propellant in some weapons is separate from the projectile. This way the weapon can fire multiple distances without changing the elevation. All of the old cannon, and firearms had this capability, where a gunner could put more or less powder into the cannon. Couldn’t this be a consideration? ---
**Author:** ![JRDelirious](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jrdelirious/32/9531_2.png) [@JRDelirious](https://boards.straightdope.com/u/JRDelirious)\ **Post date:** [July 3, 2005, 9:50pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/36 "2005-07-03T21:50:43Z")
> [@SenorBeef](#): > > Recoilless rifles are essentially tubes that launch rockets. This is to distinguish them from explosive-launched projectiles. Actually, they first of all **are** rifled, unlike a smoothbored bazooka, and do have the alternative of providing the propulsion through a cartridge charge OR being the aiming tube for a proper rocket. [Cite](http://www.answers.com/topic/recoilless-rifle). In the case of the Davy Crockett, what you have is the 105mm RR being used as launching device for a really, really big-arsed RPG. A _nuclear_ RPG. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [July 4, 2005, 4:10pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/37 "2005-07-04T16:10:02Z")
As for 20mm cannon rounds being standard FMJ… that’s not true either. US fighters usually fire either Armor Piercing/Incendiary or High Explosive/Incendiary rounds. Despite the ridiculous rate of fire, hitting other airplanes is still pretty tricky- they need all the help they can get, including HE rounds. [http://www.f-16.net/f-16\_armament\_article5.html](http://www.f-16.net/f-16_armament_article5.html) ---
**Author:** ![tomndebb](https://avatars.discourse-cdn.com/v4/letter/t/b9e5f3/32.png) [@tomndebb](https://boards.straightdope.com/u/tomndebb)\ **Post date:** [July 4, 2005, 4:42pm UTC](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510/38 "2005-07-04T16:42:03Z")
> [@Ficer67](#): > > Another possible difference is the propellant charge. The propellant in some weapons is separate from the projectile. This way the weapon can fire multiple distances without changing the elevation. All of the old cannon, and firearms had this capability, where a gunner could put more or less powder into the cannon. Couldn’t this be a consideration? Large guns certainly use this sort of propellant, but a 20mm cannon or 30mm cannon has never been loaded that way. They are fed by pre-loaded, cased amo belts, just like machine guns–hence the question of the OP. (Even the 75mm cannons they put on a few WWII aircraft came with cased propellants so that they could be fired automatically without messing around with measuring the charge.) [Previous page](https://boards.straightdope.com/t/whats-the-difference-between-a-rifle-or-gun-and-a-cannon/310510.md?page=1)