” The World Wars of the 20th century introduced machine guns” -— What about the Gatling Gun, which was used during the Civil War?
the gun you refer to is not autonomous
The Civil War era Gatling Gun was huge and unwieldy, hand cranked thing on 3 foot wheels the crew out of necessity were exposed to enemy fire, machine guns are gas fed are lighter and very portable.
“The 16th century brought rifles...”
No, smooth barreled muskets, replacing the Arquebuses of the 15th Century.
Rifles, with rifled barrels, didn’t show up until the early 19th Century, and still didn’t work well until the invention of the Minié ball, that could effectively use that rifling. It came along in 1853 during the Crimean War.
Big, heavy, box fed, and hand cranked. Belt fed machine guns were man-portable and fully automatic.
The debate on that goes back and forth, but the basic logic is that the Gatling requires external power and is actually an array of single semiauto firearms rotating around a common axis. A single barrel, single breech ‘infinite repeater’ is what more people would consider a machine gun; in fact, Gatlings were originally considered *artillery pieces* until after WW2.
The first practical and effective machine gun was Hiram Maxim’s Maxim Gun - and they’re wrong about the 20th century introducing them to the world stage. They showed up in the late 1800s during the Scramble For Africa.
In the last half of the 20th century, they added a electric motor that eliminated the hand crank.
Most notorious is the GAU-8 gun in the A10 ground support aircraft.
Fires a 30mm pill at a very high rate of fire.
Smaller versions fire the 7.62 (30 cal).