Here's a person that compared expansion on several self defense rounds. I've always like Corbon but the Winchester did the best.
THR - View Single Post - Some CCW Ammo data
He compared the following rounds.
Winchester PDX1 Bonded 9mm 124gr +P, Hornady Critical Defense 9mm 115gr, Cor-Bon Pow'R Ball 9mm 100gr +P, Federal Hydra Shock 9mm 124gr +P

He said he got 12.5 inches of penetration from the PDX1
USAF Retired, CATM, SC CWP, NH NR CWP, NRA Benefactor
To preserve liberty, it is essential that the whole body of people always possess arms, and be taught alike, especially when young, how to use them... -- Richard Henry Lee, 1787