Have you checked with mould makers? NOE makes pellet moulds and in .250" size, they have one weighing 22gr. I think that is about the same weight as a pure lead .250" round ball.
Of course, the Hades JSB pellet with tiny nose and long skirt might be the easiest "forming" pellet at 26.54gr. weight. The JSB Exact King at 25.4gr. is a much shorter pellet with a larger nose/head.