K'nex Haas Rifle
It is difficult to operate, as it was built for an extreme emphasis on range/power and nothing else.
It can use fin-stabilized dart rods IE KillerK sniper rounds.
When I have the spare time, I'll run tests to see how much range I can get it to go, how accurate it really is, etc.
In the first picture, it is unloaded and not cocked.
In the second picture, it is ready to fire a red rod full-power.
In the third picture, same as second but closer view of the mechanics.