the 5.45 round has been greatly gaining in popularity due to the cost of it. In fact there are several manufacturers now chambering AR15s in it. Before my tragic boating accident I’d bought 1080 round cases of it for ~10c/round.
True, but still not relevant for the story. The article doesn't say AK or AK-74, but clearly AK-47.
The military 5.45x39 is a great round, and has a reputation for deadliness. You're still limited to surplus (note the 1080 round case) and the vagaries of import law. If domestic manufacturers pick it up, then that will kill the savings.