I posted this first on stackoverflow before checking out this site and finding people with a similar issue.
I found a post on serverfault with a very similar problem and decided to bring the issue over here.
The situation described on the previous link is exactly what's happening for me, only I have discovered that Chromium downloads the file every time, so I assume even on IE and FF, the response is getting there, only those browsers don't download the file.
Apache seems to be causing the issue here, as bypassing it and going straight through Tomcat makes everything work.
What could be Apache doing to the request so IE and FF drop it, but not Chromium?
Any help would be greatly appreciated.