You've got that exactly backwards, they have lower BC's compared to lead core bullets of the same weight because of the density of copper being so much lower than lead.
Because they are so much longer than lead core bullets of similar weights they also typically require a faster twist rate to stabilize the bullet which is why when you get into the heavy for caliber bullets people often have a difficult time getting them to shoot well.
I totally agree but I doubt we will here from back n/a.
Cheers!