From the Miculek channel, “You’ve seen him rapidfire the beast- but this time Jerry Miculek makes an outstanding, seemingly impossible shot using a 34 pound Barrett M107 50 caliber rifle, a Vortex Razor HD gen II JM, and Hornady 750gr A-MAX ammunition.”
I know someone will ask.
The bullet hit the steel below the balloon, and shrapnel from the bullet as it came apart against the steel, popped the balloon.