Penetration
Dick, daRock, TallPaul, BMatthews (no particular order)
Penetration
I feel this is misunderstood (at least by me) as most seem to immediately cite mass (really inertia)
Undoubtedly mass and inertia have a bearing but I don’t think that is even the major factor.
Reason: Sailplanes have very light weight yet excellent penetration.
Enlighten me please.