yes

charlemagne or monty full salvo everything and never missing with all its ammo. 71ishk x 20+ =<1mil

I did 700k with 36% hitrate in a Kaiser without AA, 1 million attack is probably possible, just unlikely.

You'd have to be a very good player, playing against a very noobie fleet, with a very noobie fleet..."no one does anything, you just farm" type of game, and possibly in HA, or else you usually dont find 30 vs 30 BB6 rooms too often these days. 

You'd need a massive BB room with Nebraska or Kaiser.

The teams would probably need ships to be balanced against you, but the skill level would need to be in your favor with mostly defensive minded people.

Your team can't overrun the enemy and you can't get overrun. And, of course, every shot has got to count. 

Get an H44 in the BB1-5 room and it's also possible, but u will need like 40 vs 40.

With kaiser/H44 it's easiest. You'll also have to make sure you don't sink people outright so you can get more attack after they repair.

Stack as many ships as you can on top of eachother and blast it with a kita and nuke torps. Kita has highest possible damage output if you think about it.

As I have said before:

The answer, my friend, is bombers.