An alternative depth of penetration experiment was explored and utilized to fit a subset of Johnson–Cook strength model parameters. An RP-4-shaped charge detonator was modeled and compared with experimental data for DOP and tip velocity. The ordinary requirement of using a semi-infinite target for DOP testing was relaxed and the target geometry was altered. The outer radius of the DOP target was reduced to yield more motion of the outer, lateral surfaces of the depth of penetration target in a manner analogous to an expanding ring test. An RP-4-shaped charge penetrating a modified copper DOP block, with a reduced diameter, was modeled. Velocity data was extracted from this simulation and used as synthetic experimental data. The Johnson–Cook strength model constants for copper were fitted by using optimization to minimize the difference between the synthetic experimental data and simulation data. The approach was partially successful at reproducing the original Johnson–Cook strength model constants.