I can't really say for definite, since I don't frequent DM servers too often, and I don't usually get large KillStreaks that are important to me, to remember.
I guess, on average, if it's a fair match (Which it usually isn't) I can get around 10-15 kills as a high KillStreak. If that happens, I've tend to have had a lucky little sprint at killing. Usually happens with a Shotgun, if I manage to jump in the middle of some other peoples battle. Finish them off, then when they attack, if I'm lucky enough, I can jump to cover and finish some enemies off with an Assault Rifle of some sort.
However, It's really un-common for me to be any good at DM'ing at all. :S