At Walmart I can buy all sorts of BB guns and air rifles that shoots a pellet up to 1,800 - 2,100 feet per second. No license or waiting period required.
However you won't find them at a Walmart in Maryland or other Commie socialist liberal pinko gay tree hugging progressive states. You will find them in real American stand your ground states where murder is legal as long as you were at some point scared of your victim. Well, ya also gotta be white which goes without sayin.
They don't say how many pumps per shot it requires to fire one pellet at 2,100 FPS.
Someday there will be a truck tire attachment that will make your air rifle fully automatic. Hoowee , that wood dang sure liven up the 'ol double D truck stop/shootin range on a hot Sat. nite.