There are reports that these bits break too easily. I broke three before finally getting the speed right for the shot. Move slowly, let the weight of the drill do all the work, and just focus on keeping the machine steady so you don't break any bits. This was my first time using my drill and I had to figure out the settings. The beats are not to blame. A user error caused the bits to break. Once I figured it all out, the bits went through my concrete slab almost like clockwork. Okay, not quite like butter, but definitely effortless.