Just make the point of acting mature and resposnsible. The main reason for the age thing to my understanding has to do with legal accountability more than anything becasue of the nature of this game and the risks and hazards assoiated with it, your expected to act like an adult at all times and be responsible.
(Feel free to correct me on this If I got it wrong this is just my understanding)
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Certified Airsoft Level 2 Bolt-Action Sharp-shooter