What is "double tap"?
You might be wondering what double tap means. No, it's not a tap dancing technique. In the military, double tap refers to shooting twice in succession looking at the same target. The idea is that the second shot will be more accurate. With practice, the time between shots become shorter and shorter.
The origin of this technique was started by William Ewart Fairbaim and Eric Sykes. They were police chiefs from Britain who were working in Shanghai during the 1930s.