See No Evil - S2-E1
Visible crew/equipment: While Sandy is helping NCIS by listening to the feed, Gibbs asks her if she can "remember anything else about the train sounds," and in the next shot we can see the reflection of the boom pole/mic (being held overhead) on the steel surface behind Abby. (00:34:05)
Chosen answer: "Policing your brass", means to pick up your expended shell casings, after firing your rifle, or pistol.
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