I haven't bought 1.5 yet, still chugging along with 1.4, so there was probably one or two more guns added to 1.5. I keep a virgin backup copy of the game patched to 1.4, got August 2004 for shells.dat and June 2005 for shells.zon.
Would have been a bit simpler if they had just added comments/labels in the shells.zon file, hey?