Short answers, pulled from the story.
The Heilongjiang hand cannon is the oldest surviving firearm in human history, dating to the 2nd of May 1288. This bronze artifact was discovered in the Acheng District of modern-day Heilongjiang, China, and measures 34 centimeters in length.
The firearm evolved from bamboo fire lances in the 10th century to metal hand cannons in the 13th century, eventually leading to repeating rifles like the Spencer and Henry models used during the U.S. Civil War of 1861 to 1865. This progression included the development of the flintlock mechanism in the 17th century and the percussion cap in the early 19th century.
The Small Arms Survey reported over one billion firearms distributed globally, with 857 million held by civilians. U.S. civilians alone account for 393 million of these civilian-held firearms, representing about 46 percent of the worldwide total.
In 2017, there were 39,773 gun-related deaths in the United States, with over 60 percent being suicides. Gunshot-related homicides were the 31st most common cause of death, while gunshot-related suicides were the 21st most common cause of death in that year.
Under 26 USC § 5845, the term firearm means a weapon designed to expel a projectile by the action of an explosive, including the frame or receiver, any firearm muffler, or any destructive device. This definition distinguishes between title II NFA firearms and title I firearms not restricted by the National Firearms Act.