According to Official Guinness Records,
The most nails hammered with the head in one minute is 13 and was achieved by John Ferraro (USA) on the set of 'Guinness World Records Gone Wild!' in Los Angeles, California, USA, on 3 July 2012.Read more: Hammer Head - Pro wrestler nails world record with his forehead - Guinness World Records Italian Show
For a complete list of 2012 records, please visit 2012 Guinness Records in United States.