So from the historical side, as far as I know, the DeWilde never had tracer, or at least it was not used much by the RAF in fighters. The Buckingham tracer is what was in use in the RAF early in the war, and this is what some of the earlier Spitfires in the package have loaded in two of the guns. Standard RAF practice was to not mix different types of ammunition in a single belt. Instead, a typical Battle of Britain period ammo load for a Spitfire or Hurricane would be two guns loaded with Buckingham tracer, one with DeWilde incendiary, two with armor piercing, and three with ball. In the Spitfire package a variety of ammunition loads are represented on different aircraft depending upon when the aircraft depicted by the skin was active, and reflects how ammunition loadings evolved over the course of the first year or so of the war.
Now onto the requests for the armourer to flout the regulations and give the pilots what they want. In the weapons folder you will find the folders for the various types of .303 round that came with the package, such as SJ_gb_round_303cal_INC. SJ_gb_round_303cal_INC is a DeWilde incendiary. Suppose you want to make it a DeWilde tracer. You need to delete the .bdp file in the folder (it will regenerate itself the next time you fly) and then open the xdp in a text editor like note pad. Look for the following: TracerEffect="XXX". XXX is the name of the tracer effect as found in the effects.xml used for the round. Since XXX does not exist in the effects.xml, no effect is shown. Now open the xdp for SJ_gb_round_303cal_INCT (the Buckingham tracer), and you will see it uses a different effect - TracerEffect="tracer_303calinc". Replace XXX with tracer_303calinc and now you've got DeWilde tracers. If you don't like that particular effect, you can browse through the other rounds in your weapons folder until you find one you like. Alternatively, you can delete TracerEffect="XXX" entirely and a default tracer will be used. Now then, don't tell the Squadron Leader I told you this.
