Don,
Two millimeters! If a source for lots of rounds could be found, it might make a decent mousegun
I mean a real "mouse" gun because a few grains of lead would be huge to a 5 gram mouse - a grain per gram whereas humans only get a grain per pound. Maybe the elves could be persuaded to make some for Christmas.
Shin-Tao,
You nicely explain the advantages of such a weapon shooting 60 grain needles. Stopping power would be nil since it may take some time before the target realized they'd been perforated. But quickly stopping bleeding from all those internal and external holes would be impossible. Add a little anti-coagulant and the target would go into hemorrhagic shock. Even one or two rounds would be effective - eventually.
"What's wrong Joe, you look pale."
"I don't know. I just feel weak and my guts hurt."
"Strip. We gotta see if you got bit by something."
"Damn, he's got several little holes in his abdomen and over his kidneys. Joe, have you been peeing blood?"
"Yep"
"Oh, God! Must've been a sniper. And here we are hundreds of miles from base and we can't get an evac in here without tipping our location."
"Pete, our location is already tipped! We gotta get Joe out of here or he's done for."
"Sorry Joe"
"That's okay, you guys go on. I'll just stay here and sleep."