In CfgAmmo there are lines that define tracer colours, for example BulletSingleW:
tracerColor[]={0.8,0.5,0.1,0.04};
tracerColorR[]={0,0,0,0.005};
I imagine changing this to something like:
tracerColor[]={0,0,0,0};
tracerColorR[]={0,0,0,0.};
Might do the trick......then again I've never played with weapons and ammo much.
Planck