This mod isn't about realism, and cannon shells fly faster because they don't carry as much explosives. There were bugs before where one shells would take down another shells if fired at the same time by one vehicle.
I know it isn't about realism but there really should be at least some sort of sense what will be included in the mod and what won't. Also if you could shoot down arty's shells then the whole arty would become useless because you just could sit in your base and snipe the shells to expload long time before they would reach the enemy base.
now you do. the US army has developed a highly successful prototype laser system that can automatically track target and destroy artillery shells from mortars to battle ship artillery, rockets to ICBM's (the ICBM class one is mounted onto a heavily modified 747. some other thing it tracked, but I forget now.
I never said it fires 1.29 jigawatts of energy every half second with perfect accuracy at shells, i said it could be used for defence against a single shell. 2 shells or more artillery tanks would require more lasers.
we don't want there to be a defensive solution to every attack. the point of artilliary is that they can slowly (and i mean slowly) grind back a powerful defense. they're to get the game flowing again, because as soon as one team has artilliary, the defensive team has to go on the offensive to take them out.