What is one way to express the command "START"?

The command "START" can be succinctly and effectively expressed as "Commence Firing." This phrase accurately conveys the action of starting the shooting process in a clear and formal manner, which aligns well with the standard procedures and vocabulary typically used in air rifle training and competitive shooting environments. Using terminology like "Commence" ensures that the command is recognized as a directive to initiate the activity in a disciplined and organized way, which is crucial for maintaining safety and order during such activities.

While other options may communicate similar intentions, "Commence Firing" is the most appropriate choice within the context of air rifle sports, as it directly ties into established shooting commands and practices. Thus, it maintains consistency and clarity when relaying instructions to team members or participants.