With veterancy it's perfectly fine to use on tier buildings and Pak43. That's really all you need to know on the major. As for mobile ranged units. USF has the best one in the game with the M8A1 vehicle. It's mobile, can smoke, can phosporous. I really don't think giving USF heavy arty, insane infantry, insane long range tanks, and AoE shell Jackson's is a good idea (Especially with talk of a pershing on the Horizon). OKW doesn't even have artillery and the axis artillery isn't that strong.
Used twice a vet3 major artillery against a pak43. Only 1 shell hit the pak. Never again i'm gonna bother with it, unless we are talking about disuading a push or i don't care about the scatter.
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When people used the stupid "let's add 50% fuel cost to discuss unit performance", at least use the correct numbers.
It's been showed that it's not 66%, and more around 70-72%.