These are the rules we play with in the parking lot at Saints games. I have no idea if they have official standing or not, but they don’t seem too different from the rules I’ve seen used at other places. Feel free to email me with any corrections or additions, though.
The rules are pretty simple.
All it requires is a log, some nails, and a hammer. Typically a Machinsts’s Cross Pein hammer is used. http://www.hammersource.com/din1041.html is an example. You use the pointy end to drive the nails.
Start by starting the nails in the log. Each person then tries to drive in their nail, one swing per person, rotating around the log. You must start with the hammer on the log, lift it and hit the nail in one smooth motion. The first person to drive their nail flush with the log wins. The typical prize is a shot of apfelkorn.
Men use one hand. Women are allowed to use two.
We typically use a 1lb hammer. Most prefer a wood handle (ash is typical), but that’s more likely to get beat up on protruding nails when people miss. We also put a piece of tape on the handle and require people to keep their hands behind the tape. The tape is at a position such that is you miss entirely, the handle will hit the edge of the log above the tape, and it’s almost impossible to mash your hand if you hold the handle behind the tape.
The biggest thing is to get a log that won’t split when hit with errant blows. Practically, this means something like elm, at least 24″ in diameter, and at least 12″ thick.
Hope this helps.