To practise this shot, ... Open console ~ in main menu and type OPEN BRIDGE When map is running, open console (~) again and type CLASS G Now you have the M203 grenade launcher.
You can follow you 203 nade's flying path by opening your console again and type BIND P VIEWCLASS PROJECTILE By shooting your nadelauncher now, and by pressing P after hitting the trigger, the 203 nade will be followed. You can apply any key to this action, I chose P voor Projectile. This will also work with rockets.
First get your ass over to this little weed here.
Then look down and make sure you crouch right on top of it.
See those 2 trees? Well, ... aim right in between them. The Next picture will show you exactly how to aim.
I used to T-shaped HUD for this one. As you can see, you can perfectly line this HUD on top and between both trees. Now hit the trigger 15 second after the round starts. Mostly this will be like 4.45 or 9.45 minutes. Depends on server settings.
Your nade will land and hit exactly in the middle of the defence towers arch and hit anyone heading for the bridge.