Click - Shoot Space - Use scope R - Load a new shot (mandatory if you want 10 bullets)
Credits to @Reptlowagain / Reptlow (they are the same person) INSTEAD OF ONE STUPID BULLET YOU GET 10 , HOW'S THAT? Pretty cool right? But when you start you get one bullet (because a bug in the code), so just reload and it fixes it. For some reason it shoots automatically too.