[mattrick]

It seems odd to me that a rifle was deemed too dangerous to use in a populated area but a pound of C4 strapped to a robot was acceptable.

[bombcar]

The blast radius is much easier (cube law) whereas a .50 cal bullet could go for miles.

[mattkrause]

It seems odd to me they had a pound of C4 laying around!

I suppose it's a demolition charge for deactivating bombs?

[MerelyMortal]

A bullet can travel further than a blast.

[ethanbond]

And bounce in less predictable ways