Can you fire an AEmitter from a device and have it pin to the very gun that shot it?

No.

You can attach an emitter to the device, but it'll always be attached and you can't link it to the firing cycle in any way.

Are you sure Lua couldn't detect the fire button input and activate the emitter?

Also there's the whole x-flip problem with emitters.

Unless you make a custom scene and force people to load it through the Campaign menu, yes, I'm quite sure of that.

Well that limitation is pretty much a given, when someone suggests Lua.

I just get a bit sick of mentioning it for the sake of acknowledgment whenever questioning the capabilities of Lua.