To be blunt....... Fobus is crap.
In every class I've taken or taught, a Fobus has either broken or it has "locked" the pistol in so tight you nearly tore the pants belt loops getting the pistol out.
Get a Blade-Tech or a Comp-Tac Kydex and live happily from now on.
The Fobus was also my first holster. Probably will not have a problem with your P99 falling out with this holster. Alternative choices would be either the C-T.A.C. or a Gunleather rig. But of course, go what fits and is useful to you.
My Fobus has been okay. It is my first holster and was extremely tight when I first bought it, but now it is pretty smooth and I still have no worries of it falling out. Guess it just needed time to break in and for me to get the technique down. Okay holster for the price...
With that said, I am now looking to upgrade to a nice leather one...looking for something a little smoother and for something with class
I know it's not a tactical rig, but for off-duty carry, I use Galco's Fletch High-Ride (#FL418B www.usgalco.com)
I have tried a lot of off-duty stuff and most of it is crap. This is one instance where you get what you pay for. I carried my Ruger P93 for a lot of years and the Galco rig is by far the most comfortable. (It now sits in my gun locker after being replaced with the .40 P-99!)
I used a fobus for a long time. Initially it was too tight. I heated with a hair drier and boiling water and it helped a lot. In retrospect I don't know why as Fobus is not Kydex, but it did.
If you snap the pistol straight up it helps too. Towards the end, I took a piece of paper and wedged it between the halves at the trigger guard to force them apart a touch (still plenty of retention) and it got better.
I've since moved on to better quality kydex holsters for all my stuff. You can make fobus better, but they are still slower on the draw than Kydex from the better makers IMHO.