Interest in understanding the response of particles to low-energy (incremental) breakage has increased significantly in comminution in recent years, mainly due to the recognition that a large proportion of impacts in tumbling mills is insufficient to cause breakage at the first collision event. Likewise, degradation during handling is another field in which low-energy breakage is of great relevance. The investigation of this mode of breakage, however, is very tedious when conducted in drop weight testers, so that more convenient alternatives for testing have been sought. A device, called JK Rapid Breakage Tester (JKRBT), has been proposed as a more convenient alternative to other breakage testers, mainly the Drop Weight Tester, being used in recent studies that investigate incremental breakage. The present work demonstrates, through experiments and simulations, that care should be exercised when using this device in investigating breakage by low-energy impacts, since testing of iron ore pellets resulted in significantly more breakage than expected, when compared to a drop test. This has been confirmed by simulations using the discrete element method, which demonstrated that ricocheting of a fraction of particles can happen against the rotor, resulting in overestimation of breakage for the set energy level. Such effect has been observed to be relevant not only in the case of nearly spherical shapes, such as the iron ore pellets studied, but also in the case of very irregularly-shaped particles.