for some additional info/clarification on lingo:
"live" rounds are any rounds that can be fired. blanks are modified rounds that still have a primer & powder, but the projectile portion is replaced (often with something like paper wadding). even without a situation like a squib load (which is what killed Brandon Lee), a blank can still be deadly - Jon-Erik Hexum accidentally killed himself when he discharged a weapon loaded with blanks at point-blank range against his temple. blanks are used when they want to simulate things like flash, bang, and recoil.
a "cold" gun has no rounds in it capable of being fired (which means no blanks, either). it may be completely empty, or it may contain dummy rounds - these would usually be used when there is no firing going on (so no need for flash/bang/recoil), but when the places rounds would be expected to be are visible, like in a revolver. dummy rounds have no primer or powder. they can still be dangerous when combined with blanks.