Thanks for your prompt reply. You've confirmed that I'm not going mad, but something is still not right with this, as I am not noticing any change in weapon effectiveness re the changes I am making to "blast radius" and "kill ratings"...
...So, I took your advice and did a test, setting the "blast size" to -1, ie, no blast, for Arty Explosion. I did the same for the German 8cm mortar so I could compare. The mortar worked as expected, but the barrage was unchanged!?!?!?
Without anything else to go on, my conclusion is that the Ground Tactics Mod is using a different weapon for the mortar barrage??? I have read davidss' readme file, but couldn't find anything to this effect. How do I check that out and change it? Or do I need to contact davidss and if so, how do I do that?