Bastic bullet

Bastic bullets were projectiles capable of penetrating Dalek casings. Orcini destroyed a Dalek on Necros by firing bastic bullets at it. (DW: Revelation of the Daleks)

Eventually, Dalek force field technology advanced to the point where bastic bullets were no longer effective against them. This was the case in the Battle of the Game Station in 200,100. (DW: The Parting of the Ways)