This skill has major applications in military and law enforcement work, like when snipers need to eliminate two hostage takers at precisely the same instant. I first learned the techniques involved when the Canadian government paid me to pull triggers. But while sniper work is a lot different than hunting, there are some skills that carry over, and synchronized shooting is one.
The thermometer in my friend's truck claimed it was minus 30 degrees the morning after Black Friday, but we went hunting anyway. And after doing some coyote killing at one place, we moved on to another and pulled a stalk on an area where a farmer dumps dead livestock. It's not unusual to find a coyote patrolling here, and this frigid morning there were two. With nothing fresh to eat, these scavengers were just sitting on a large mound, enjoying the view, dreaming of a dead cow and soaking up some early morning sun.
Our stalk took us to a fence line 158 yards away, and from there we elected to shoot. My friend took the right target, I took the left, and moments later two dead coyotes did a simultaneous slide down the snow-covered mound (photo above). We killed those coyotes within a split-second of each other by using a technique I've adapted for hunting.
With no spotters, communications gear or operational commanders to issue green light orders, hunting is much simpler than sniping. Additionally, hunters will usually be next to each other and not separated by a multi-story building or across a parking lot. With that in mind, and assuming both shoot right-handed, I designate the person on the left to do a verbal count which the other shooter can hear. The person on the left should do this because the manner in which we hold rifles orients the counter's mouth toward the other hunter, who naturally has an ear oriented to the counter.
The count is done at a steady, even pace and only goes to "three," with both shooters learning the cadence during those first three numbers. Then, both fire their rifles at "four," although the word is never uttered, remaining only an imaginary point in time. It sounds like: One . . . two . . . three . . . BANG! There should be a 1-second gap between each word and the subsequent shot.
The reason "four," the unheard signal to fire, is not verbalized is because it's so difficult for the counter to speak and shoot accurately at the same time. Also, the counter will likely pull the trigger when he starts to say "four," while his partner won't shoot until he's reacted to hearing the word, a gap which can be substantial. Leaving the "four" unsaid gives both shooters the freedom to react to exactly the same thing, the cadence of the count. Reacting to the same signal means two shots at the same time, which is the entire goal of the exercise.
It's a good idea to practice this at the range before trying it in the field. Although, practicing it while shooting rodents such as prairie dogs is great training, too. It's not a technique you'll use every day, but once learned, is a useful item to have in a shooter's toolbox.