[Raeiphon]

A scope, laserdot, whatever. When you're sniping, you press D to scope/unscope and S to fire. Scoping cloaks you and places you in the prone state.

Time to simplify:
If you get caught prone, you're very likely dead. Higher damage weapons will have less cloaking power, while lighter more mobile weapons will have more cloaking power at the expense of damage. All sniper rounds are subject to random bullet drop over the 2 level mark. Bullet velocity is roughly 50-60 xy per second. All enemy sniper shots in range of you are flagged with a crosshair on the radar until you reload, otherwise they are invisible to it. Cloaking percentage is the chance not to be detected by eye when enemy players move close to you. The calculation that determines whether you are exposed or not triggers every 5 seconds.