Cool looking... Very possible the twisting could have caused the cracks... The early zincolns were in sad shape plating wise... I suspect that due to contamination in the plating tank or on the blank zinc core and heat generated during the strike caused a separation between the copper and zinc... When twisted it would pop and split at the weakest spots... The copper is only 2.5% of the total weight so the plating is really thin... If memory serves me correctly, split plating is partially related to the actual strike and also the copper being stretched to the point of breaking open!!!