Help the Bombardier! I'm the Bombardier!

Don't even try to do it with one hit in one group. Use two shots. First one goes to a group at top stairs and second to a group at 2nd stairs from bottom. The farer the shot takes longer to hit. Put this achiev on tracker so you'll see that after first shot you got like 4 seconds to hit with another shot. When doing right, those 2 shots should hit in same time.

Yeah. It has already been said, but I'll clarify it.

The achievement _actually_ is a kill window. It doesn't measure the deaths with a single shot. Once you kill one soldier, a timer (I believe 4 seconds) starts counting down, during which time you have to kill the remaining 9. This leads me to believe that the daily is actually designed to be done the following way, despite the text:

There's a concept in artillery in the real world known as MRSI, or multiple rounds simultaneous impact. Simple explanation: shots at targets farther away take longer to travel, so if you have a gun that fires fast enough, you can fire multiple rounds at different targets and have them all impact at the same time. I timed it. Firing at the farthest away group which walks the ramp into the temple takes about 11-12 seconds between click and impact. Firing at the closest groups takes 5-6 seconds. So watch the far group for a bit until you figure out a good place to drop a round to take as many out as you can. As soon as you've fired that round, look at the closest groups for a second target. You must fire the second round as soon as the 5 second cooldown has elapsed.

Using this method, even if you're relatively sloppy with both shots, you can easily get the achievement.

This is a reference to the book Catch-22 by Joseph Heller.