>>508237786
>>508238235
Honestly given what WWII era bunker busters were able to do it’s not that unbelievable.
>two Grand Slams went through the 15 ft (4.5 m) reinforced concrete hardening—equalling or exceeding the best current penetration specifications.
4.5 is a far cry from 60, but it’s also a pretty primitive 1939 era bomb. Given improvements in weapons design I would doubt it struggling with 40 meters with 60 being in the air
Picrel is the grand slam