Head and lubricated piston

A head assembly comprising:

• a piston head for making a piston of a press for a die-casting machine, comprising:
• a head body having a side wall extending around a head axis, and
• at least one ring seat obtained in the side wall and suitable to receive a respective sealing ring, the at least one ring seat forming a cylindrical bottom wall parallel to the head axis and being delimited by at least one annular shoulder obtained in the head body;
• and
• a sealing ring housed in the at least one ring seat, wherein at least one gap is formed between said sealing ring and the at least one annular shoulder;
• wherein:
• a lubrication circuit is obtained in the head body and is suitable to facilitate the sliding of the piston in a respective container of the die-casting machine,
• the lubrication circuit comprises at least one lubrication end duct leading into the at least one ring seat so as to be covered by the sealing ring, and
• at least one lubrication end duct leads into a surface channel which runs through the bottom wall, said surface channel ending at a base of said at least one annular shoulder in order to convey a lubricant towards the at least one gap for the outflow of the lubricant from the at least one gap.