More likely he has in mind some kind of experimental weaponized biological or encased supertoxic radioactive isotope. Hopefully never made surplus by accident. But the caution is valid because mistakes are occasionally made. Short of launching it into the sun, there's never any such thing as 100% certainty that something hazardous you make will be contained forever, nor even that it is perfectly destroyed. Humans may do their best, but only God is perfect.
The pointed bullets look about like any match bullet. The 175 grain Sierra MatchKing used in M118LR ammunition comes to mind as close, but that wouldn't be as old as the 1950's and their weight tends to be pretty consistently as named.
