If the Jackson were reduced to 160 damage sure, but as it stands Jacksons are just too damaging to be able to stand with another Heavy Tank. They have that damage because USF lacks a Heavy Tank.
Jackson has such a slow reload, the 240 damage still leaves it doing less DPS than an SU-85
No late game? Jackson? Stop using them as meatshields and you will be fine, trust us lol
And what should you use as meat shields? There is little to stop a German player from driving even a P4 through your lines and killing the Jackson. That and maps with lots of shot blockers really wreck the Jackson.