roadrunner
WKR
Thin jacket and no bonding.
Your assertion that extra bullet length- which in this case means increased SD, in a fragmenting bullet doesn’t cause increased penetration is objectively false. When a thin jacketed, fragmenting bullet remains point forward, the longer it is- all else being equal, the deeper it penetrates at the same impact velocity. There is simply more bullet to fragment (lose) while still maintaining sufficient mass to continue penetration.
WHOA! So energy does matter. You just stated the two components of the mechanical system the directly relate to energy.
Well done! I knew you'd get there eventually