Early cutoff distance for particles?

I’m currently making a firebeam with Shuriken particles and would like to control the distance at which particles cut off. Like so:

I currently achieve this using collisions, however this method causes the problem where individual particles may miss the collided object:

Is there a way I could make it function like image A? Something like making the emission cone the whole collider or something? I can get it to work by adjusting start lifetime, but I don’t know how to correlate that with raycast distance.

Turns out that I just needed a high school formula: speed = distance/time :smiley: