Playing shooters, I've often wondered if the persistent knowledge of exactly how many rounds you have left delivers a tactical advantage you can't have in real life. This invention delivers a video-game advantage to the battlefield.
This device - fixed to an automatic weapon, no less - counts the rounds remaining in the magazine. It's hard to tell if it's getting it right all the time, but there's a burst at about the 1:00 mark that the humans incorrectly identify as four rounds, but the gizmo correctly ticks off five.
The maker, MichaelCiuffo on YouTube, says he's taking orders.
Now if they can only invent something that instantaneously fills your partially spent clip with exactly the amount necessary for a full clip when you reload. Preferably by hitting X.
Bullet Counter Official Test [YouTube, thanks Dean]