Getting NEW posts from a subreddit in JSON

How would I go about getting the new posts of a subreddit in JSON? Just tacking on .json to the url (http://www.reddit.com/r/SOME_SUBREDDIT/new.json) returns the following:

{
    kind: "Listing"
    -
    data: {
        modhash: ""
        children: [ ]
        after: null
        before: null
    }
}

The children array doesn't contain any posts. I've come to find that http://www.reddit.com/r/SOME_SUBREDDIT/new actually routes to new?sort=rising when what I need is new?sort=new.

and /new?sort=new.json of course wont work.