Four diagonal lines appear around your weapon's reticule when you connect with a shot. Most likely you won't notice it while actively shooting at someone because your eyes will be focused on the opponent's movements, but toss a grenade at a guy around a corner and you can see them plain as day. If anything, go into custom and toss a grenade at a guest's feet to see the markers.
Sony bought Konami and will release a DDR game for the Nintendo DS. In this game, you set your DS on the floor and stomp on it till it no longer functions.
I only pay attention to them when tossing nades that I'm not sure will hit someone or if I'm shooting past my weapon's effective range, meaning when the crosshairs are no longer red despite aiming at an enemy.
From: Duwstai | #004
Honestly I havent noticed them once since the game released. What do they even look like?
Little markers at each corner outside of the crosshair every time you shoot/grenade an enemy/vehicle. Looks like a separated X.