: For Grunts on Legendary, I suspect that the plasma pistol is more effective
: than the needler. They have good accuracy and a high rate of fire, and
: obviously the shots travel faster than needles, so threats can potentially
: be neutralized sooner (e.g. before combat Flood get close enough to fire
: or melee). In the movie you can see some snappy plasma fire around 1:15
: for example.

looking at the video again the plasma pistol does seem much more effective against the combat forms than the needler especially as they close the range between them and the Grunts.