The Massifier is a top-of-the-line, state-of-the-art mass manipulating device.

It's primary function is decreasing the mass of any massive body by turning the particle's mass into negative mass. Low exposure reduces the mass of the body greatly, making it easier to change it's momentum. Prolonged exposure, however, results in negative net mass. What does this mean? Effectively, if it interacts with another massive object (i.e., collides) the resulting force applied to it won't follow the expected direction, but the opposing one. For example, jetpacks will not help the user fly, but will push it towards the ground. Violently.

It's highly unadvised to make physical contact with negative mass bodies.

Seems neat, though oddly ineffective sometimes and very effective others. I'm still trying to get a feel for it.
You've got a lua error somewhere when it loses its target I think, and you've got a lot of stuff (info) printing to the console.

Yeah, it prints the mass of the target everytime it casts the ray, I thought it was useful at least, I liked messing around I guess people would have liked it, but it's not a big drawback.

And the lua error is when it doesn't have a valid target. That, or maybe nil magazine, though I think I removed that problem last time I checked. Yes, the mod is quite unpolished, I wanted to make it better but I've been quite busy lately. I'll try to get around to it later today if I can and fix some errors.

Add a check at line 9 to be sure target's not nil, that'll probably fix your errors. Also you don't have the raycast ignoring self.Team, I don't know if that's deliberate though.

Fair enough about the mass, after realising what it was it is useful since it lets you see how light the target's become, which gives you a better sense of the gun's effect.

Uploaded a fixed version and slightly more powerful so it's more lethal.