81mm, 82mm, Grw 34 and 120mm mortars gets 106 and 140 AA range. Only the USF mortar used to have this and the rest were only for BARRAGE.
MHTs (USF/OH), Pack Howie and ISG* only benefits of an increase range on barrage on vet3.
*vet1 gives it +5 range
now little katitof takes pack howie shells and amazing barrage mode into account
Regarding the Pack Howie. Till it hits vet2, barrage mode shells are equal to auto attack shells. If you try to use the range on the pack howie barrage (shooting an enemy base into FoW), you'll find yourselves hitting 1/15 on the desired spot.
If the enemy has lots of units spread out, yeah you will be hitting something.