China has a massive military. Just like any other people, most of the soldiers would have been turned into zombies during the initial phase of the apocalypse. Those zombies would have no use for their weapons. So, where are all those weapons, aside from the random few assault rifles we've seen? Smart folks should have already searched garrisons and military storage places for heavy machine guns, mortars, APCs/IFVs. Tanks are pretty cumbersome, especially if you wanted to move them elsewhere.