Different than the one I'm thinking of, but good find still.I think this is the clip you're talking about, I found it in a /vt/ post from September of last year which was captioned "Sleepy at her gun range": https://files.catbox.moe/hvd8yd.mp4
For reference, the /vt/ post: https://warosu.org/vt/thread/85442297#p85517921