Those blessed Slow Mo Guys are back with a bit of a military physics lesson masquerading as a super cool video where bullets fly at 120,000 frames per second. Gavin Free and Dan Gruchy’s latest frame-by-frame exploration gives us a clear look at a plane-mounted, fixed armament firing without damaging the propeller (or throwing away its shot).

It’s mesmerizing to look at because of the interplay of the two objects: the bullets come unbelievably close to grazing the propeller blades, but the sync gear (a World War I innovation) only allows the machine gun to fire between the blades as they rotate, and at the speed they’re both going, every shot is a close call by definition. The result is a beautifully satisfying, coordinated dance of high speed objects. On that same front, the video puts into context how much faster the bullet travels compared to the blade. You can see how the latter almost freezes while the bullet sails by.

Granted, they had to keep the propeller at a much lower speed than normal in order to keep it stationary, which makes the brilliance of the sync gear even more impressive.

The basics of that brilliance are a rod and cam that connect the machine gun to the propeller, interrupting the gun’s firing capability when the bullet would go tearing through the blade. Luckily for us, the Slow Mo Guys are willing to destroy a blade to show us what happens when the sync gear isn’t turned on.

Image: The Slow Mo Guys