[akdavis]

To get this to work for the .303's you first need to have the mod which gives the .303's the smoketrail file. The .303 smoke tracer mod is include (to my certain knowledge) in the ui 1.2 or in one of the spitfire mods. If anyone can submit it to a file shring site, then I'd be happy to include it in my initial post in this subject

Unfortunately, the Spitfire .303 tracer mod folder in UI 1.2 is empty.

As far as I can tell, the following do not have smoke trails:

German 7.92mm
Russian 7.62mm
British .303 (with exceptions, e.g. Mosquito FBVI and Hurri IID)
US .30 (with exceptions, e.g. A-20C)
Italian 7.7mm
Japanese 7.7mm (with exceptions, e.g. Zero)
Italian 12.7 (with exceptions, e.g. Re2000)
Russian 12.7mm

Also the new Avia and Fokker don't have smoke trails, but I don't know if they share with something above.

Now, I'm not sure if this is to be expected, or if there is some conflict with HSFX4.