Based on a previous round-robin exercise of the German DVM task group on “Instrumented Impact Testing” with about 400 instrumented Charpy-specimens being tested, another exercise was performed to explore the possibilities of extended evaluations such as single-specimen methods. The previously determined multi-specimen cleavage J_R-curve serves as a reference. Different methods — e.g., the key-curve method — were applied. Overall, the results are encouraging and the agreement of the calculated J_R-curve with reference data is quite good especially for large amounts of crack extension. There was some uncertainty left in the first part of the J_R-curve, where notch blunting and initiation of crack growth take place, and where the calculated curves tend to overestimate the crack resistance. Results of a new “blind” round-robin indicate improved results in this initial part of the J_R-curve.