I got some pretty much identical boxes of GI ammo but it was loaded in the 90's. Should be no problems. If the codes on the lid match the years of the ammo, like if it is 57 and 66 as I suspect, it should be perfectly fine. If the ammo is mixed up with different headstamps, it might be reloaded like the man said. Only other factor might be how it was stored over the many years. But bad storage would only probably serve to cause reliability problems, like squib loads or duds. If the ammo is still bright and shiny or at least no green stuff on it, I would feel fine with it.