Surley in a 1v1 conventional war between China and the US, the first one to cross the Pacific Ocean loses. I'm fairly certain neither has the capability to sustain an invasion of the other.
The Chinese actually do not use AKs. They use a bulpup called the Type 95. The estimated cost to equip a Chinese infantryman is $1,500 (the rifle is $700). While the average cost of a US infantryman is estimated to be $17,500 according to an article in the Walstreet Jounal. The Chinese have 19,538,534 people reaching military age annually compared to America's 4,217,412 giving China the advantage in numbers and the ability to sustain a war over time.
America's advantage is quality. The US' large defense spending is partly because of all the hardware it builds. America has 14,000 aircraft compared to China's 3,000. 20 aircraft carriers compared to China's 2ish. America has around 50,000 armoured vehickles compared to China's 15,000. Much of America's equipment is cutting edge tech like the 8000 M1a2 Abrahms tanks compared to 9000 of China's more cost efficient type 99 tanks.