A Waffenamt-Prüfwesen 1 report estimated that with the M4 angled 30 degrees sidewards, the Sherman's glacis plate was invulnerable to shots from the Tiger's 8.8 cm KwK 36 L/56 and that the Panther, with its 7.5 cm KwK 42 L/70, would have to close in to 100 meters to achieve a penetration in the same situation.