I wonder if there is some confusion due to the dual lines of EFMJ available. Federal makes both a consumer version with a light bullet to make up for being standard pressure, and a +P LEO version. The LEO version, from tests I've read, penetrates very well, definitely satisfying the FBI standards. The lighter bullet, of course, doesn't do nearly as well. I think that the LEO 124-grain +P 9mm averages about 15" through four layers of denim, while the 105-grain consumer version gets about 9".
Expansion size is traded for guaranteed expansion. Federal EFMJ in 9mm expands to only about 50 caliber, but it does it through anything. It expands through sheet metal, windshields, drywall, 20 layers of denim, wood, etc.
If I sound a little biased, it's because I like the stuff. I've found it to be very accurate out of Kahr pistols.