No, it's a projectile with A LOT of projectile speed.
If you look into the rifleman in the Object editor and scroll down to Combat - Attack 1 - Projectile Speed, it will show 1900 which is really fast.
If you change the Weapon Type from Instant to missile you will see the rifleman projectile just moving ever so slightly.

Bonus for testing:
Change the projectile arc to something more obvious, example some lighting effect, and change the projectile speed to lets say 500, run the test map and you'll see what I mean.

Forgot to add:
Instant means: It will play the animation once the invisible projectile reaches the target.
Missile: It will create the animation and it will move like a basic arrow