You're almost there!!
Inside the Data/Library folder, open the "Shells.dat" file. All the specific ammunition types are there. The 3_50 is found under the "88mm_" headings. The 4_50's are under the "105mm_" name. The 5_25 are under "5_25Inch_" group (go figure!). Follow the id's of the specific ammunition found in this file, to match the id's in the .sim files your looking in.
That 3_50 AP shell: ID=0x7cf440f1c98196cc........see if it isn't under the Parent ID of the node #32-33 of the Shells.zon file?