The only problem with orient particles is it's an Emitter function, and projectiles are only allowed to a single trail emitter, which is unfortunate. Otherwise I would have stuck filler Dots to make the lasers seem a bit less "flat" when looking into them.
This is what I mean:

Of course it's either this or a line of dots. As long as you don't zoom in it's not bad at all.
Edit: Also useEmitterColours does not work with projectiles, so the laser's stuck to a single colour.