helping in edit md3.cfg ?

[makkE]

It's not a vertex, it's a triangle. Just import one of the original guns and you can see it at the end of the barrel.

Just make a triangle like that, move it slightly in front of your barrel and put it in it's own group and name it "tag_muzzle"

For animation: you need to re-animate the throwing motion, I'm afraid. As floppy said, refer to the frames used in it's original cfg.