Be it known that we Charles Le Holden and William Knedler citizens the United States residing at Kings Mills in the county of Warren and State of Ohio have invented certain new and useful Improvements in Bullets of which the following is a specification.

Our invention relates to bullets or balls for cartridges such as are used in rifles pistols and the like and has for one of its objects the provision of simple and efficient means for rendering a bullet highly effective for holding itself intact and in shape during flighty.

(...)

The fluid will tend to be driven through the core 1 thus giving a maximum flattening or mushrooming effect to the bullet when the latter engages a target This gives great killing power to the bullet when the latter is used for hunting game and the like.

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Moreover the bullet in preserving its unity on despite high velocities and not broken has greater penetration after mushrooming thus greatly enhancing its killing power.

Bullet terminal performance

A factor that has become more and more prominent in discussions of killing power is the terminal performance of hunting bullets. Assuming a rifle of reasonably adequate caliber, selecting the right bullet for the job can play a big role in killing power. Big game should be hunted only with bullets designed for the purpose. Frangible varmint type bullets and FMJ military type bullets are unsuitable for any type of big game hunting, and are illegal in most jurisdictions.

David “Carbine” Williams and the Invention of the M1 Carbine*

When World War II broke out, the U.S. military needed a weapon to combat the new fighting tactics of German forces. Support troops needed guns that were lighter than standard service rifles so that they could go about their normal duties. But they also needed guns that were more effective in combat than the pistols they had been using. The Ordnance Department asked for design proposals from both military and civilian designers.
 
Williams at the time was working for Winchester Repeating Firearms Company in Connecticut. Winchester decided at the last minute to enter a light rifle prototype in the competition. An important part of this rifle was Williams’s short-stroke gas piston, which he had worked on in prison. After several weeks of tests and a number of modifications, Winchester’s entry, the Carbine Caliber .30 M1, was adopted as the standard rifle for military service. 

The M1 carbine, as it came to be known, went from a design on paper to a weapon in the hands of soldiers in less than a year.

Nope, guns are designed to project lead (or paint or plastic) pellets where the barrel is pointed. The pointing of the barrel, and the decision of when (or if) to pull the trigger is what decides the use case of a gun.

Statistically, it's almost never to actually kill something.