The 19th century brought unprecedented changes to weaponry. Thanks to the Industrial Revolution and interchangeable parts, guns evolved from clumsy and inaccurate muskets to lethally precise rifles between the years 1789 and 1864. In addition, the revolver and machine gun introduced weapons that could fire numerous shots in a single round. Weapons like the Colt revolver were new but popular firearms in this period.

Percussion Cap

In 1805, Reverend John Forsyth of Aberdeenshire, Scotland, patented the percussion cap. The percussion cap allowed guns to use a non-exposed flash pan for initial ignition. This had the advantage of minimizing dampness in moist conditions. In addition, the percussion cap was more reliable than its predecessor, the flash pan. It operated by having an automated hammer strike a small cup filled with mercury. This cup was attached to the tube of the gun. Forsyth's technology relied on the chemical properties of mercury, which explodes when struck. Once the hammer struck the mercury-filled cap, an explosion lit the gun's powder and propelled the bullet out. The percussion cap was perfected over subsequent decades, and was adopted by both the British and American armies by the 1840s.

Colt Revolver

Before the invention of the revolver, guns could only shoot one bullet at a time before reload. In 1836, Samuel Colt received a U.S. patent for the Colt revolver, which included a revolving cylinder loaded with five or six bullets. Gunpowder and bullets were both loaded into the revolver, and six bullets could be loaded in about 20 seconds. Colt invented different models, including a pistol, rifle and a holster. Weapons produced by Colt were used in both the Mexican-American War and in the American Civil War. Colt, a Connecticut native, refused to sell guns to Confederate states after the outbreak of war, however.

Rifling and the Minié Ball

Before 1849, loading guns remained difficult because most bullets conformed to the size of the barrel in which they were loaded. This meant that significant force was required to lodge the bullet into the gun, which slowed down reloading times. In 1849, however, the French army officer Claude-Etienne Minié invented a bullet that was hollow iron and expanded when fired. This meant the bullet could be easily loaded into the gun because it was smaller, but still fire accurately because it wouldn't bounce off the sides of the barrel. The Minié bullet, as it was called, was accurate to 200 to 250 yards. It was first used during the Crimean War, and was later used by both the Union and the Confederacy in the American Civil War. In the United States, it was colloquially called the "minnie ball."

Gatling Gun

The world's first machine gun was invented in 1862 for the purposes of the American Civil War. The Gatling Gun, named after its inventor Richard Jordan Gatling, could fire up to 400 rounds in one minute, an exponential increase over other guns available at the time. Gatling's original model could only shoot 200 rounds per minute, though that was still a large improvement over other available firearms. The gun operated with a multi-barreled cylinder that turned so that only one barrel shot at a time. This allowed the other barrels to cool and be prepared to shoot again shortly thereafter. In the Civil War, the gun was used in the siege of Petersburg, Virginia, in 1864.