Editing Smoothbore (section)

==History==
{{further|External ballistics}}
{{For|pre-20th-century smoothbore artillery|Cannon}}
Early firearms had smoothly bored barrels that fired [[projectile]]s without significant spin.<ref name="Fadala2006">{{cite book|last=Fadala|first=Sam|title=The Complete Blackpowder Handbook|url=https://books.google.com/books?id=Dzxyneq43AEC&pg=PA308|date=17 November 2006|publisher=Gun Digest Books|location=Iola, Wisconsin|isbn=0-89689-390-1|page=308}}</ref> To minimize inaccuracy-inducing tumbling during flight, their projectiles required an aerodynamically uniform shape, such as a [[sphere]].  However, surface imperfections on the projectile and/or the barrel will cause even a sphere to rotate randomly during flight, and the [[Magnus effect]] will curve it off the intended trajectory when spinning on any axis not parallel to the direction of travel.<ref name="Forge2012">{{cite book|last=Forge|first=John|title=Designed to Kill: The Case Against Weapons Research: The Case Against Weapons Research|url=https://books.google.com/books?id=2sV_xBayWGcC&pg=PA63|date=24 December 2012|publisher=Springer|isbn=978-94-007-5736-3|pages=63–64}}</ref>

[[Rifling]] the bore surface with spiral grooves or [[polygonal rifling|polygonal valleys]] imparts a stabilizing  [[Gyroscope|gyroscopic]] spin to a projectile that prevents tumbling in flight. Not only does this more than counter Magnus-induced drift, but it allows a longer, more streamlined round with greater [[sectional density]] to be fired from the same [[caliber]] barrel, improving the [[accuracy]], [[effective range#Weapons|effective range]] and [[terminal ballistics|hitting power]].

In the eighteenth century, the standard infantry arm was the smoothbore [[musket]]; although rifled muskets were introduced in the early 18th century and had more power and range, they did not become the norm until the middle of the 19th century, when the [[Minié ball]] increased their rate of fire to match that of smoothbores.<ref name="Denny2011">{{cite book|last=Denny|first=Mark|title=Their Arrows Will Darken the Sun: The Evolution and Science of Ballistics|url=https://books.google.com/books?id=H0yt17cHgeQC&pg=PA53|date=1 May 2011|publisher=JHU Press|isbn=978-0-8018-9981-2|page=53}}</ref>

[[Artillery]] weapons were smoothbore until the mid-19th century, and smoothbores continued in limited use until the late 19th century. Early rifled artillery pieces were patented by [[Joseph Whitworth]] and [[William Armstrong, 1st Baron Armstrong|William Armstrong]] in the United Kingdom in 1855. In the United States, rifled small arms and artillery were gradually adopted during the [[American Civil War]]. However, heavy coast defense [[Rodman gun|Rodman smoothbores]] persisted in the US until 1900 due to the tendency of the Civil War's heavy [[Parrott rifle]]s to burst and lack of funding for replacement weapons.