You're experiencing the reason I don't care for .380s. Non-expanding bullets in that caliber have a long history of poor "stopping power," for want of a better term, and are likely to overpenetrate. The hollow points don't generally penetrate as deeply as most of us want.
Buffalo Bore is a well-made product, and I know folks who carry BB .380 +P in their LCPs and shoot it with no ill effect on the gun. Since the factory recommends against the hotter .380 loads for that gun, I'd limit how much of it went through the gun.
Hornady 90 grain XTP is the closest I can find to a balance of decent penetration with at least some expansion, but honestly, I'd be advising you to turn the page in the Ruger catalog to the LC9 pistol or the LCR .38 Special.