I was thinking about it, and the limiting factor on how many people you can kill with a semi-automatic burst is 1/2 your skill level.
So...
Adept with 13 skill and improved ability 6 has a skill of 19. half of that (rounding up) is 10 targets.
that's 3.3 people per bullet, or to put it another way it's 330% more bullet, per bullet!