A C-130 is built for rugged landing strips, and thus has the inherent maneuverability needed for the work. It may not be a fighter, but it can accelerate decently and turboprops have a pretty good response time, plus a C-130 can climb nicely.
C5? It can haul a lot of weight, and go long distances, but it takes huge runways with a slow climb speed and can't exactly turn on a dime. That, and the airframes are pretty old now. Due to age they are slapping more and more limitations on them regarding flight conditions.
Volume is one thing, but you need to get down low and get it in the right spot. Otherwise, it's a wasted effort as you'll either miss or it will dissipate too much.