S!
+1 to everything said before, and about the tracer colors:
Russian:
MGs: Bright green
Cannon: White
British:
MGs: Red
Cannon: Yellow
German:
MGs:
7,9mm: Red
13mm: Blue
Cannon:
20mm:Cyan
30mm: Yellow
(These come in combinations of 7,9mm+20mm / 13mm+20mm / 13mm+30mm, so no 7,9mm(red)+30mm(yellow) together).
US:
MGs (.50cal): Pink(ish)
Japan:
MGs: Red
Cannon: Yellow
So, looking at this, at least German, US and Russian tracers should always stand out from the rest. And since the brits and japanese rarely have fights online, it's pretty easy to know who is who, if they happen to fire that is
