For the record: The UH CEO shooter wasn't "clearing a jam" after every shot...
From the manuafactuer’s webpage for that model: “This model in 9mm wears a 3-in. barrel. It finds its operational success as a magazine-fed, non-auto-ejecting single-shot functioning in a rotational bolt action.” This is a feature, not a bug. Casings make noise when they eject and hit the ground. If you want a truly silent gun, you have to manually expend the casing. Preferably into your hand to leave no trace.