You shouldn't be copying the model and sound files from the Gun. If your weapon uses them, edit the script to reference "Add-Ons/Weapon_Gun/pistol.dts" etc. instead of "./pistol.dts".
The colour files go with the model to control textures. The blank, whiteCheck and black/greyXX (25, 50, 75) textures are partially transparent and blend to the item's colorShiftColor while the others are just solid shades of colour. For instance, the Wand in base/data/shapes has the ends textured with blank.png to be shifted to the colour of various other wands (Wand is white, Destructo Wand is red, Duplicator is green with one model) and the shaft is textured black to always stay that colour.