I am trying to improve my gunnery and tactics as a machine gunner. Special Tactics has an e-book on this very subject and I went onto a practice mission I self-edited in Arma 3.
On this topic of MG employment, the book mentions planning for bullet dispersion and ricochet. Bullet dispersion is because of the movement of the gun or the (designed) cone of fire MGs produce. Further dispersion can result from ricochets. So, it is important to have in mind bullet dispersion and ricochets to not hit your own troops maneuvering onto a target area.
The book shows the following diagram to provide guidelines on what areas are to be considered.
The diagram shows a top down vision of the important areas: dispersion area (10 degrees centered from the gun aim point) and the ricochet area (10 degrees further from the dispersion area).
In the Arma 3 vignette, I am to provide MG fire support with an M60 to a squad of US Marines closing into an enemy occupied house.
Here are some screenshots of the target area.
There are 2 ENY MGs in this house and I better suppress them for good to give my Marines a chance to get there.
The red line in the screenshot above shows the trajectory of my rounds (there is an Arma 3 script for that). As you can see, there is a dispersion cone but the fire is grazing and not plunging. The range is just 300 meters, so no surprises there.
But I have also observed some ricochets from my fire. See the blue line coming out of the house at an angle. Bullets do weird things sometimes.
So, it is important not to fire when the Marines are close to the objective house.
I observed this very funny thing: due to the incoming fire, one of the ENY machine gunners moved into the house and positioned himself in a keyhole position of sorts (see below). It think it is just a happy accident and not due to the AI of the game entities. My rounds can be seen coming from the distance.
All theory was fine and cute, but in the haste of appearing cool and professional I forgot the most important thing. The morning haze hid my Marines, and at a certain point I was shooting above their heads. That was really bad manners.
Having realized of the hazard I was imposing on my men, I had to cut out my fire support and watch with upmost nervousness how the assault unfolded.
Fortunately, the Marines succeeded. We have been very lucky not to get hit by rounds fired from and at the target area!