Installing Mavericks 10.9.4
You can only download it at all if you have it in your Purchase History on the App Store, &amp; even then you'd get 10.9.5

Other than that, you'd need to find a friend who archives OS versions meticulously.
If you can get hold of 10.9.anything, you can then use the combo updater to 10.9.4 from Apple.