Bullets are not standard-compliant impact elements
Bullets that only correspond to the correct mass are not standard-compliant impact elements and therefore not permitted for tests according to EN 60068-2-75. There are standards in which steel bullets are specified (e.g. EN60601) but this is explicitly not the case with EN 60068-2-75. The bullet has a different mass diameter ratio as well as a different speed on impact. It cannot be assumed that the same joule number achieves the standard-compliant result if the impact element deviates from the specifications. Especially with bullet diameters that are too small, the impact load is much higher than with correct diameters.