Getting into I-banking in a bulge bracket firm is really hard to do as you mentionned. You are probably right when you say that earning your MS in Finance from a small school probably won't give you many chances of getting in Goldman or some other bulge bracket school. But I would think that with your military background you should have an edge on the competition (*think* being a keyword here).
But what would prevent you from getting into Berkely, Princeton etc... ?
The better the school the better your chances
Again my advise is really not that great, and I don't know much. I am doing an MSc in Finance in London at LSE this fall, and after a lot of research I found out that my chances of getting into a bulge bracket firm in London are good. But again, that is after carefully considering the school, and asking every single person I know about it.
To your original question: a master in Finance won't hurt you for an MBA; whether it gets you into a bulge bracket firm, that I don't really know.
Good luck to you, you should check out this forum if you have more questions about it: ibtalk.com . It's mainly for Brits, but they have a lot of good advices on it. You should look at what programs you are considering and ask them a question there.
The MS Finance section of the gmatclub is almost dead apart from one or two post every months. I got most of my info from other forums regarding my MS in Finance.