This is basically only one effect -modified tracersmoke I use now in my WW2 install, it will be included in the upcoming Unified Effects Pack update as an optional file.
It's slightly different from my tracer smoke from WW2 effects pack (2007), looks more like tracer smoke you see in BOB2:WOV
extract to your Effects folder
please note that without serious modding of the bulletobject.ini file ALL guns share single effect for their smoketrails, which is ok, but if you're going for maximum visual realism , there should be several different smoketrails for different types of guns. I might try to do something about it in the future, but free time and you know, don't want to promise too much