“
You do the double shift like this (Figure 81 A, B, C, D, E): Telegraph that you are about to shoot a straight left at your opponent's head. Shoot the left, which he'll evade by stepping back. Then, immediately stride forward with your right foot, and (as you stride) shoot a straight right at the head. If he's fast, he'll avoid that one too, but narrowly. Then, immediately stride forward with your left foot and (as you } stride) shoot a straight left at his head. Put everything you've got into that left, for it's almost sure to nail him. The double shift is designed to force a retreating opponent to (1) step back from the first left, and (2) immediately spring away frantically to avoid the unorthodox right that should (3) leave him flustered and unprepared to avoid the final unorthodox left.
It is called the "double shift" because your body is shifting to the southpaw stance as you throw the right and shifting back to the normal stance as you shoot the last left.
The combination of movements should be made with utmost speed and savagery-with your fists going whoosh! -whoosh!-BOOM!
Even if you miss him with the last left, you'll be back in normal punching position, ready to work on an opponent who should be extremely flustered.
Some fighters use the double shift with hooks instead of straight punches. The late Stanley Ketchel, a "wild man" slugger, used the shift with overhand swings, landing on the side of an opponent's jaw and neck with thumb-knuckle and wrist. Stanley must have had cast-iron hands.
I would advise you not to attempt the double shift with hooks, for your long strides will open the hooks into swings or semi-swings. Moreover, use of the hooks will leave you dangerously open as your body turns at the beginning of each shift.
”
”
Jack Dempsey (Toledo arts: championship fighting and agressive defence (Martial arts))