Is a giant 8 gauge shotgun.
Being able to propel a mass at high velocity in a controllable and reliable manner is very useful.
As Wee'rd says: "Obviously defensive, military, sport, and food-harvesting applications are where guns shine... Guns are tools, some less mature people may not LIKE the jobs they’re good for, but that doesn’t make them any less tools."
And for the curious here's my comment on Weer'd's where I explain my wiki-wander