Sorry for digging up a zombie thread...
They were letting in Felonies and GEDs a few years back....
Since felons aren't allowed to arm up, I find this very difficult to believe.
As for your situation, most of the above posts are correct. DoD is making budget cuts and a large portion of those cuts are coming from payroll. This means that entry requirements have been raised.
I'm currently in on a marijuana waiver but I joined ten years ago. It is possible to join but unlikely at this time.
You should provide your state/county so you can be directed to have the conviction expunged. That's your best option. Even if it's sealed or expunged your security clearance investigation will reveal it. The difference will be that it has been taken care of vice just sitting there as an open conviction. It's not a guarantee that you'll get in, but it does improve your chances. Good luck.