Editing Shell (projectile) (section)

===Rifled breech loaders===
{{main|Rifled breech loader}}
[[File:Sagahan Armstrong gun used at the Battle of Ueno against the Shogitai 1868.jpg|thumb|The [[Armstrong gun]] was a pivotal development for modern artillery as the first practical [[rifled breech loader]]. Pictured, deployed by [[Japan]] during the [[Boshin war]] (1868–69).]]
Advances in metallurgy in the industrial era allowed for the construction of [[rifled breech loader|rifled breech-loading guns]] that could fire at a much greater [[muzzle velocity]]. After the British artillery was shown up in the [[Crimean War]] as having barely changed since the [[Napoleonic Wars]], the industrialist [[William Armstrong, 1st Baron Armstrong|William Armstrong]] was awarded a contract by the government to design a new piece of artillery. Production started in 1855 at the [[Elswick Ordnance Company]] and the [[Royal Arsenal]] at [[Woolwich]].<ref>{{cite journal |last=Bastable |first=Marshall J. |year=1992 |title=From Breechloaders to Monster Guns: Sir William Armstrong and the Invention of Modern Artillery, 1854–1880 |journal=Technology and Culture |doi=10.2307/3105857 |volume=33 |issue=2 |pages=213–247 |jstor=3105857|s2cid=112105821 }}</ref><ref>{{Cite web|url=https://www.gracesguide.co.uk/William_Armstrong|title=William George Armstrong - Graces Guide|website=www.gracesguide.co.uk}}</ref>

The piece was [[rifling|rifled]], which allowed for a much more accurate and powerful action. Although rifling had been tried on small arms since the 15th century, the necessary machinery to accurately rifle artillery only became available in the mid-19th century. [[Martin von Wahrendorff]] and [[Joseph Whitworth]] independently produced rifled cannons in the 1840s, but it was Armstrong's gun that was first to see widespread use during the Crimean War.<ref>{{cite web |url=http://www.au.af.mil/au/awc/awcgate/gabrmetz/gabr001b.htm |archive-url=https://web.archive.org/web/19990819063641/http://www.au.af.mil/au/awc/awcgate/gabrmetz/gabr001b.htm |url-status=dead |archive-date=19 August 1999 |title=The Emergence of Modern War}}</ref> The [[cast iron]] shell of the Armstrong gun was similar in shape to a [[Minié ball]] and had a thin lead coating which made it fractionally larger than the gun's bore and which engaged with the gun's [[rifling]] grooves to impart spin to the shell. This spin, together with the elimination of [[British ordnance terms#Windage|windage]] as a result of the tight fit, enabled the gun to achieve greater range and accuracy than existing smooth-bore muzzle-loaders with a smaller powder charge.

The gun was also a breech-loader. Although attempts at breech-loading mechanisms had been made since medieval times, the essential engineering problem was that the mechanism could not withstand the explosive charge. It was only with the advances in [[metallurgy]] and [[precision engineering]] capabilities during the [[Industrial Revolution]] that Armstrong was able to construct a viable solution. Another innovative feature was what Armstrong called its "grip", which was essentially a [[squeeze bore]]; the 6 inches of the bore at the muzzle end was of slightly smaller diameter, which centered the shell before it left the barrel and at the same time slightly [[swage]]d down its lead coating, reducing its diameter and slightly improving its ballistic qualities.

Rifled guns were also developed elsewhere – by Major Giovanni Cavalli and Baron [[Martin von Wahrendorff]] in Sweden, [[Krupp]] in Germany and the [[Wiard rifle|Wiard gun]] in the United States.<ref>Hogg, pp. 80–83.</ref> However, rifled barrels required some means of engaging the shell with the rifling. Lead coated shells were used with the [[Armstrong gun]], but were not satisfactory so studded projectiles were adopted. However, these did not seal the gap between shell and barrel. Wads at the shell base were also tried without success.

In 1878, the British adopted a copper "[[Gas check|gas-check]]" at the base of their studded projectiles and in 1879 tried a rotating gas check to replace the studs, leading to the 1881 automatic gas-check. This was soon followed by the Vavaseur copper [[driving band]] as part of the projectile. The driving band rotated the projectile, centered it in the bore and prevented gas escaping forwards. A driving band has to be soft but tough enough to prevent stripping by rotational and engraving stresses. [[Copper]] is generally most suitable but [[cupronickel]] or [[gilding metal]] were also used.<ref name="Hogg pg 165 - 166">Hogg, pp. 165–166.</ref>