Abstract: The penetration potential of shaped charges is proportional to the jet length and the square root of the jet density. The bulk-sound velocities of the liner materials define the maximum possible jet tip velocities. The jet tip velocities and breakup, or particulation, times determine the jet length. For shaped-charge optimisations these parameters have to be considered. After a brief discussion of these issues, this paper outlines the potential of a range of materials for use as a possible shaped-charge liner. It is further noted that, as well as the selection of optimal materials, a number of other factors have be taken into account, such as quality of the raw material, homogeneity, and grain-size distribution. Finally, the paper describes the different production possibilities for copper liners, identifying the advantages and disadvantages of each. In particular, the flow-turning process is discussed with its potential for spin compensation.