Ok, so for a request for Gotcha! I want to make a one-use healing gun. After browsing the LuaDocs, I see two possible ways to do the self-gibbing. One, it looks like there's an "IsActivated" function on HeldDevices, so could I do this in Update()?

Or, another way Grif said is the option, having a particle do the Lua in it's Create() function. Would the particle be able to access that which it was fired from, like self.Parent.GibThis()?

EDIT: Got that done.
NOW, how do I retrieve a method from a dofile? I tried dofile("file"):method(params);, but that failed mightily, as well as just plain dofile("file"); and later self:method(params);, and the same but without the self:.

Couldn't you just give it a ridiculously high fire rate, fullauto, have the healing thing set as the tracer and a self destruct particle as the main round?
If you make the main round hitsmos and non-fireignoresthis with the muzzleoffset inside the gun the gun will self destruct after one use.

Did it. It seems that the HDFirearm's update(self) is not called until it is out of an Actor's hands. I followed 411570N3's advice and made the particles do the work, both health-ing and gibbing.

NOW, how do I retrieve a method from a dofile? I tried dofile("file"):method(params);, but that failed mightily, as well as just plain dofile("file"); and later self:method(params);, and the same but without the self:.

What? A function and a method are very different. Just dofile("myfile"); at the top, and any functions defined in that file will be loaded and usable.

Got it now. Thanks Daman.