Increasing Arrow Speed

I'm playing Minecraft and I want to create a sort of "gun". Nothing special, just a bow with some slight twists. Decreasing the draw speed is no problem, I already have that figured out. The one thing I'm struggling with is finding a command to make the arrows travel faster.

Is there a command for that, and if there is, can anyone tell me how to use it?

Solution 1:

You can modify the Motion data tag which specifies in how many blocks per second an entity is moving an each axis.
Use this command for 1.14.4:
/data merge entity (arrow's UUID){Motion:[xmovement, ymovement, zmovement]}
Replace (arrow's UUID) with appropiate selector for your Arrow and xmovement, ymovement and zmovement with the desired movement values. This will change the Arrow's speed as well as its damage.