[spoiler]

Greens add up to a maximum of pure green (thus RGB(0,255,0)), which is NOT normal behavior.
I haven't tested the blues, but the reds add up to a fiery orange.
The greens, as seen in the screenshot - only add up to a maximal green, instead of further going into whites.
It's not a critical bug, since it can be fixed by tinting the greens - but it's still a pretty damn bad looking issue.
And here's a test .pk3, summon "Testshot" for a green projectile, and "Testshot2" for a red one.
Note the huge difference in their looks. The former one uses a pure green range, the latter a pure red one.
I probably should've posted this elsewhere, but I can't really find a topic/forum more relevant to the subject.