Jump on the box! Next, you must stand on box so that the sight of AAA (anti-armor attachment) is exactly inside the crooked square (or it looks like a crooked inverted trapezoid lying on its side, nvm). Enlarged cutout from orig. screenshot

Don't forget to make a quick save. After that, make a shoot during the jump, try to shoot as low as possible and close to barrels.

If you do everything on first try, you will save some time + with this improvement you can easily make several attempts.

Love it