# Advantages of smoothbore barrels. **URL:** \ **Category:** Factual Questions\ **Created:** [February 22, 2013, 6:46am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059 "2013-02-22T06:46:10Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [February 23, 2013, 7:17am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/21 "2013-02-23T07:17:34Z")
> [@AK84](#): > > Most modern tank use smoothbore guns, which is a reversal of a trend going back nearly 200 years. **Why cannot smoothbores be used for handguns** , machine gunsm artillery pieces etc. The stability issue is resolved using fins and while it might be difficult for personal firearms, why not for crew served weapons? Recoil from the much higher velocities could become unmanagable for handheld firearms. We’re not talking about black powder muzzle velocities. There’s the equal and opposite reaction to consider. Double the speed that a bullet exits a barrel and you quadruple the kinetic energy it has. And the recoil goes up accordingly. While smoothbore barrels don’t stabilize rounds as well as rifled barrels, they can fire rounds at much higher velocities. The Rheinmetall 120 mm tank gun can reach a muzzle velocity of 5700+ fps but I’m not sure of that projectiles weight. Adding rifling to the barrel would only slow the projectile down. The M256 gun barrel weighs a recoil reducing 1,190 kg (2,600 lb) and the gun mount weighs 3,317 kg (7,310 lb) according to wiki. Then there’s the spin rate or rate of twist to consider. Spin an object too fast and centrifical force could tear the object apart in flight. Using a muzzle velocity of 3000 fps, a 1 in 12 twist would result in a 180,000 rpm. Change the twist rate to 1 in 8 and you’re looking at 270,000 rpm. At 5700 fps and 1 in 12 twist, the projectile would be turning 342,000 rpm. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [February 23, 2013, 4:00pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/22 "2013-02-23T16:00:19Z")
> [@jz78817](#): > > You’ve just described the [Foster slug.](http://en.wikipedia.org/wiki/Shotgun_slug#Foster_Slugs) Or the [shaped lead pellets used in pellet guns.](http://www.shutterstock.com/pic-74657170/stock-photo-close-up-view-of-large-pile-of-lead-bb-pellets.html) Basically any shape that puts the center of mass forward of the center of aerodynamic drag will be stable in flight. ---
**Author:** ![Dissonance](https://avatars.discourse-cdn.com/v4/letter/d/85f322/32.png) [@Dissonance](https://boards.straightdope.com/u/Dissonance)\ **Post date:** [February 23, 2013, 5:08pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/23 "2013-02-23T17:08:45Z")
> [@the\_diego](#): > > The leopard had basically the same gun as the Abrams. You’ve got this backwards, from the M1A1 on the Abrams had the exact same gun as all models of the Leopard II, the German [Rheinmetall 120 mm gun](http://en.wikipedia.org/wiki/Rheinmetall_120_mm_gun). ---
**Author:** ![the\_diego](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@the\_diego](https://boards.straightdope.com/u/the_diego)\ **Post date:** [February 23, 2013, 10:44pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/24 "2013-02-23T22:44:06Z")
Erm… that’s what I meant. The US hasn’t designed a MBT gun in more than 30 years. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [February 24, 2013, 5:12pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/25 "2013-02-24T17:12:33Z")
> [@the\_diego](#): > > Point taken bout the Le Clerc. The leopard had basically the same gun as the Abrams. The trouble with smooth bores is they don’t work that well with heavy full-caliber slugs at long range. That only really matters in tank-versus-tank warfare, which doesn’t really happen anymore. ---
**Author:** ![MichaelEmouse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/michaelemouse/32/101_2.png) [@MichaelEmouse](https://boards.straightdope.com/u/MichaelEmouse)\ **Post date:** [February 24, 2013, 5:19pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/26 "2013-02-24T17:19:09Z")
Even for tank vs tank, full caliber slugs are hardly used. From what I understand, tank guns today pretty much only fire APFSDS, HEAT missiles\*, HEAT non-missile rounds, HESH, HE and shotgun-of-doom shells. \*Yes, a tube gun that fires a missile. ---
**Author:** ![AK84](https://avatars.discourse-cdn.com/v4/letter/a/85e7bf/32.png) [@AK84](https://boards.straightdope.com/u/AK84)\ **Post date:** [February 24, 2013, 5:27pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/27 "2013-02-24T17:27:28Z")
> [@the\_diego](#): > > Erm… that’s what I meant. The US hasn’t designed a MBT gun in more than 30 years. I think even longer than that, the previous standard was the 105mm, L7, which was a Royal Ordanance gun. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [February 24, 2013, 7:16pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/28 "2013-02-24T19:16:19Z")
> [@Alessan](#): > > Pistols, yes, but military rifles are all about making small holes. True, but what I meant was that there wouldn’t be any advantage to firing a discarding sabot round out of a rifle- having a 3mm penetrator go straight through at 3000 fps might well be less wounding than a 5.56 bullet going at 2000 fps. In other words, having the really high velocity needle-style penetrator makes great sense out of a tank gun, but the same thing doesn’t hold for a rifle (or pistol). ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [February 25, 2013, 12:46am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/29 "2013-02-25T00:46:05Z")
> [@doorhinge](#): > > Recoil from the much higher velocities could become unmanagable for handheld firearms. We’re not talking about black powder muzzle velocities. There’s the equal and opposite reaction to consider. Double the speed that a bullet exits a barrel and you quadruple the kinetic energy it has. And the recoil goes up accordingly. No, recoil is a function of momentum not energy. Momentum only goes up linearly with velocity. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [February 25, 2013, 1:18am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/30 "2013-02-25T01:18:50Z")
> [@solosam](#): > > I’m speculating here, but wouldn’t a spinning sabot screw up the projectile’s trajectory when it came time to seperate from the projectile? > [@jz78817](#): > > Seems to work ok for sabot shotgun slugs. But aren’t shotguns smooth bores (as described upthread)? Do people use rifled shotguns for DS deer-hunting rounds? Also, the DS deer rounds I’ve seen haven’t been fin-stabilized, but they were mass-forward as also described above. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [February 25, 2013, 1:38am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/31 "2013-02-25T01:38:55Z")
> [@Ethilrist](#): > > But aren’t shotguns smooth bores (as described upthread)? Do people use rifled shotguns for DS deer-hunting rounds? Also, the DS deer rounds I’ve seen haven’t been fin-stabilized, but they were mass-forward as also described above. Shotguns can be had with smoothbore slug barrels (like mine) which are designed for Foster- or Brenneke-style slugs. Both slug types are of the “mass forward of aerodynamic drag center” concept for stabilization. You can also get slug barrels with rifled choke tubes, and fully rifled slug barrels. Both types are best used with sabot slugs. ---
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [February 25, 2013, 5:30am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/32 "2013-02-25T05:30:04Z")
> [@Princhester](#): > > No, recoil is a function of momentum not energy. Momentum only goes up linearly with velocity. I didn’t intend to suggest that recoil quadruples at a rate similar to a bullets KE. Yes, the increase in the rate of recoil is much closer to the rate of increase of bullet momentum (bullet mass x bullet velocity). The actual rate of recoil depends several other factors. Calculating recoil is a real PITA. One formula for measuring recoil: Recoil energy = 0.5 x {[(bullet mass x bullet velocity) + (powder charge mass x powder charge velocity) / 1000] squared } / Gun mass. Approximate charge velocities are: Black powder: 685.8 m/s (2250 ft/s) (fast burn rate propellants) Pistol and Shotgun powder: 1707 m/s (5600 ft/s) (medium burn rate propellants) Rifle powder: 1585 m/s (5200 ft/s) (slow burn rate propellants) BMG powder: 1433 m/s (4700 ft/s) > **[Recoil energy](https://guns.fandom.com/wiki/Recoil_energy)** > > Recoil energy is the measured energy in translational kinetic energy (Et) imparted to the shooter of a firearm when discharged and is expressed in Joule (J) or Foot-pound force (ft-lbf). Recoil energy, sometimes called “free recoil”, is a byproduct... I don’t know what the powder charge mass or the powder charge velocity would be for the 120mm gun’s rounds. I do find it interesting that the faster powders reach 5600+ fps. That just happens to be similar to the published upper limit (5700 fps) of the 120mm gun’s muzzle velocity. Is it possible that the smoothbore Rheinmetall L55 (6.6 m/22 ft barrel) 120mm gun has reached the maximum possible velocity of available powders??? A projectile can’t travel faster than the velocity of the expanding gas behind it. ---
**Author:** ![the\_diego](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@the\_diego](https://boards.straightdope.com/u/the_diego)\ **Post date:** [February 25, 2013, 5:46am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/33 "2013-02-25T05:46:31Z")
Lots of other variables in a gun that can allow you to increase velocity for a given projectile. One is grain size for a given powder type and amount. That changes your combustion rate. Another is manner of ignition. If you ignite the powder from the primer base, you often have un-burnt powder leaving the muzzle. Ignite it beginning around 1/3 up the casing will burn the powder better, significantly lowering chamber pressure, and allowing you to gob in more powder than previously allowed. Another is free bore. If the projectile is chambered immediately in contract with either the rifling or the bore itself (in the case of a smoothbore) you get better accuracy but high chamber pressure. Provide the barrel a free-bore segment will also significantly reduce chamber pressure. ---
**Author:** ![doorhinge](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@doorhinge](https://boards.straightdope.com/u/doorhinge)\ **Post date:** [February 25, 2013, 6:11am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/34 "2013-02-25T06:11:29Z")
> [@Ethilrist](#): > > But aren’t shotguns smooth bores (as described upthread)? Do people use rifled shotguns for DS deer-hunting rounds? Also, the DS deer rounds I’ve seen haven’t been fin-stabilized, but they were mass-forward as also described above. Rifled shotgun barrels are intended for use with single projectile rounds (slugs), not multi-projectile shot shells. Rifled barrels will produce smaller groupings than smoothbore barrels when using slugs. Spinning a slug (or bullet, arrow, football) uses gyroscopic inertia to equal out any imbalance the slug might have. The slug will travel straighter with less yaw. Spinning shot causes the shot to flare out faster than it would if it wasn’t spun. Fire shot thru a rifled barrel and the shot would travel in an increasing larger donut pattern. All of the shot would be near the outer ring with no shot remaining in the middle. ---
**Author:** ![AdamF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/adamf/32/6246_2.png) [@AdamF](https://boards.straightdope.com/u/AdamF)\ **Post date:** [February 25, 2013, 1:55pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/35 "2013-02-25T13:55:48Z")
> [@AK84](#): > > Most modern tank use smoothbore guns, which is a reversal of a trend going back nearly 200 years. Why cannot smoothbores be used for handguns, machine gunsm artillery pieces etc. The stability issue is resolved using fins and while it might be difficult for personal firearms, why not for crew served weapons? As has been mentioned previously, there are two ways to passively stabilize a bullet: fins and spin. When deciding between the two, the important parameter is the ratio between the length of the projectile and its diameter (length in calibers). The larger the ratio, the more difficult it is to spin-stabilize and the more effective fins become. Therefore, spin-stabilized (SS) projectiles are usually less than 4 calibers long, and fin-stabilized (FS) are more than 10 calibers long. And while smooth-bore barrel can only fire FS ammo, a rifled barrel can fire both kinds. Long FS projectiles have better aerodynamics and better penetration, but are more complicated and thus more expensive. Short SS projectiles can carry larger explosive charge. Tank guns care most about penetration, so they need to be able to fire FS ammo, and smooth-bore cannons are better at that. Personal firearms also care about penetration, but at common muzzle velocities (900m/s) the FS advantages are less pronounced and cannot trump the extra cost. Just about every other application cares more about the explosive charge, so SS ammo is preferable. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [February 25, 2013, 10:44pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/36 "2013-02-25T22:44:47Z")
> [@doorhinge](#): > > Spinning a slug (or bullet, arrow, football) uses gyroscopic inertia to equal out any imbalance the slug might have. The slug will travel straighter with less yaw. There are two approaches to gaining accuracy via rifling. The one you have mostly described is used by all modern rifles using metallic cased ammo. These rely on the gyroscopic stability of a fast spinning projectile and require fast twist rifling. Many rifled shotguns, air rifles, and traditional muzzle loaders use an older approach. These fire either a round ball or an aerodynamically stable, mass forward-drag producing tail, projectile. These projectiles will remain generally stable when fired from a smooth bore. The rifling spins the projectile so that imperfections average out. The projectile then flies in a mild corkscrew trajectory rather than hooking or slicing wildly off in one direction or the other. This produces much tighter groupings than smooth bore arms. Your description mentioned averaging, but the averaging of error, and gyroscopic stability are really two different mechanisms and you seem to be combining them. Some rifled shotguns do have fast twist barrels that will stabilize a mass-rearward bullet, as do many modern muzzle loading rifles. Air rifles are still all slow-twist and depend on shuttlecock shaped pellets for stability AFAIK. ---
**Author:** ![AdamF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/adamf/32/6246_2.png) [@AdamF](https://boards.straightdope.com/u/AdamF)\ **Post date:** [February 26, 2013, 11:36am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/37 "2013-02-26T11:36:56Z")
@ Kevbo Out of curiosity, can you post a link to a rifled shotgun or modern rifled muzzle loader? ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [February 26, 2013, 11:44am UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/38 "2013-02-26T11:44:00Z")
> [@AdamF](#): > > @ Kevbo > > Out of curiosity, can you post a link to a rifled shotgun or modern rifled muzzle loader? [rifled shotgun barrels.](http://www.cabelas.com/product/Shooting/Firearm-Components/Barrels-Chokes%7C/pc/104792580/c/104717880/sc/104202180/Remingtonreg-870-Replacement-Shotgun-Barrels/705659.uts?destination=%2Fcatalog%2Fbrowse%2Fshooting-firearm-components-barrels-chokes%2F_%2FN-1100237%2FNs-CATEGORY_SEQ_104202180%3FWTz_l%3DSBC%253BMMcat104792580%253Bcat104717880&WTz_l=SBC%3BMMcat104792580%3Bcat104717880%3Bcat104202180) [modern muzzleloading rifle.](http://www.cabelas.com/product/Shooting/Black-Powder/Rifles%7C/pc/104792580/c/104701680/sc/104533380/ThompsonCenter-Impact-MuzzleloaderScope-and-Gun-Case-Combo-BluedBlack/1383253.uts?destination=%2Fcatalog%2Fbrowse%2Fshooting-black-powder-rifles%2F_%2FN-1100200%2FNs-CATEGORY_SEQ_104533380%3FWTz_l%3DSBC%253BMMcat104792580%253Bcat104701680&WTz_l=SBC%3BMMcat104792580%3Bcat104701680%3Bcat104533380) ---
**Author:** ![AdamF](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/adamf/32/6246_2.png) [@AdamF](https://boards.straightdope.com/u/AdamF)\ **Post date:** [February 26, 2013, 6:37pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/39 "2013-02-26T18:37:43Z")
Very interesting. Do you know what is the advantage of rifled shotgun over a traditional rifle? It seems to me that a rifle would be lighter and cheaper. IMO, if I ever wanted to go traditional with a muzzle loader, I’d get a 4 foot, 12 pound musket (like the great-great-great grandfather used) and not a modern plastic contraption with optical sights. /rant ---
**Author:** ![Miltonyz](https://avatars.discourse-cdn.com/v4/letter/m/85f322/32.png) [@Miltonyz](https://boards.straightdope.com/u/Miltonyz)\ **Post date:** [February 26, 2013, 7:13pm UTC](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059/40 "2013-02-26T19:13:06Z")
> [@AdamF](#): > > Very interesting. Do you know what is the advantage of rifled shotgun over a traditional rifle? It seems to me that a rifle would be lighter and cheaper. > > IMO, if I ever wanted to go traditional with a muzzle loader, I’d get a 4 foot, 12 pound musket (like the great-great-great grandfather used) and not a modern plastic contraption with optical sights. /rant Depending on your location rifle hunting might be banned. In Michigan sections of the state are shotgun only for deer. I beleive it has to do with population density. A lot of people here run rifled barrels for the increased accuarcy at range. [Previous page](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059.md?page=1) [Next page](https://boards.straightdope.com/t/advantages-of-smoothbore-barrels/651059.md?page=3)