19th century premature burials?

I ume it would be possible, technically, to escape from a coffin, although very difficult. Remember legal burials are '6 feet under' At the beginning of the Millenium Trilogy by Stieg Larrson (The Girl who Kicked the Hornet's Nest), the heroine, Lisbeth Salander, actually escapes from 'premature burial' after a shot to the head, but that plot provided that she had been buried in a shallow grave without a coffin. Getting out of a Victorian coffin would be difficult, however. Remember that there would be a heavy weight of soil on top and punching through would be very difficult, particularly for someone who was not in the best of health!