Yes i know i was quite lucky in this game always winning the arty first shoots but when his aa was next to my fighter and i build an arty in range to get his aa down to not hit my fighter it shoot 2 times! before my arty wasnt allowed to shoot once. And his aa was in sight range all the time
http://www.battledexgame.com/game.php?game_id=19785

I didnt watch replay, just general comment:

If you build new arty, it will shoot first time at tick 50. AA can shoot on tick 1 and and tick 34.

Pls post turn number next time. It is much easier to find it.

Didnt actually now that. But then i have another question: I am asuming that a heavy will shoot at same ticks as aa right? so why his arty shoot once after my heavy shoot once and not twice in this game in turn 6?
http://www.battledexgame.com/game.php?game_id=19772

You need to think of the firing like a cool down. An AA load its weapons and fires about every 33 ticks. So it should shot on ticks 33, 66 and 100 when it is new. If there is nothing in range, it won't shoot, but it's gun will be loaded and ready. If there is nothing in range on tick 100, it waits. Next turn, if something comes in range on tick 1- whenever it fires. Thus, it could fire on tick 1, 34, and 68 for that turn. Every turn it fires on different ticks depening on whether things were in range.

A new heavy fires on the same tick as a new AA. But once either of them misses a shot because nothing is in range, they fire on totally different schedules.

It can shoot on ticks 1 and 34, but it can also shoot on ticks 33 and 66 ( and anything in between ). It needs 33 ticks to reload. If it didnt shoot at all in previous turn, then it should shoot at tick 1. If it shot in last tick of the previous turn, than it will shoot first time at tick 33.