uh yes... but i know very little about it
so this is my best guess, but i'd check by looking on google and waiting for replies by people who know what they're talking about more
end of disclaimer
thinking about it mechanically, you probably want a straight line from your first two knuckles through your wrist down your forearm - you want to transfer the force from hand to arm with no extra stress on the wrist joint - that means no bending of the wrist joint. So you try for perfect form first and then worry about how hard you are doing it - start gently with good form, as for most things
hang on i'm sure there was a thread about punching at some point ... lemme have a look ...