Copper and stainless steel used in neutrino related experiments have been screened for primordial and cosmogenic isotopes with highly sensitive germanium gamma spectroscopy. Aliquots of these materials have been exposed to cosmic rays at the LNGS site. The obtained production rates (saturation activities) are checked against experimental and theoretical literature values. The data is used to evaluate the cosmic ray exposure histories of the originally measured samples. Two stainless steel samples offer the possibility to compare the obtained exposure ages with a time scale based on the disequilibrium in the thorium decay chain.