The Firing range is a facility on Galactica that allows her crew to maintain their small arms proficiency.
Apollo and Starbuck are conducting target practice on the firing range when the oxygen to the room reaches dangerously low levels. They overcome their hypoxic delirium long enough to shoot out the glass of the pressurized door, allowing air to reach them.
The drop in air pressure was apparently caused by the effects of the Cylon logic bomb. After Sharon Valerii is revealed to be a Cylon sleeper agent, some of the crew post images of her face on the targets (Flight of the Phoenix).
