Is there a way to create a bullet that goes faster the longer it exists? I tried doing negative air resistance first, but that didn't work. Would there be another way to do this besides using a mass-emitting AEmitter attached to an MOSRotating?

With lua, sure. Or AEmitters.

Thanks dog.

If I recall correctly particles disappear if they are flying faster than some arbitrary value (500 comes to mind, but I am not sure), so you'd probably also want to add a check for that before changing velocity further.

Also, Lua scripts run per frame, and since the FPS can fluctuate while in-game time remains the same (or vice versa), that script will accelerate your particle at different rates based on FPS, and won't be consistent with the in-game time.

Do yall know if this script works with MOSRotatings? I'm doing this with an autocannon-based weapon, adding it to the round causes a could not match property error, and adding it to the MOSRotating does nothing, no matter how high the value.

In the script, it needs to be "Vel", not "vel". Capital "V". Attaching it to the MOSRotating should work fine.

You could multiply by delta time if that's possible, I don't really remember.

edit: Seems like you can only find the fixed delta time that the game tries to run simulation at. Oh well

You can have a timer to check the exact amount of time elapsed since the last frame.