MWAG,
Just for informational purposes, both Bruce and I have driven bullets softer than that to higher velocities than you will achieve with the 380.
The thing that will play the biggest point in leading or accuracy is size of the bullet not the hardness. Fit is first and foremost, then harness in relationship to pressure behind the bullet. A bullet may not lead at 1000fps with one powder and lead like crazy at 1000fps with a different one.
The one will be with a faster powder and have much higher pressure the other a slow powder with much less.
For a ballpark there is a formula to determine what the pressure should be per bullet hardness. 1440 x BHN = psi.
1440 x 18 = 25920psi. I noticed that most loads from Hodgdon don't make that pressure, although they are listed in CUP not psi.
Take a chance on them. If they don't work all you will have is a 2" to 3" barrel to clean. Not like a 22" rifle barrel.