Does anyone know where I can get a mold for a .512, 600 grain bullet for my 50-90 that I won't have to mortgage the house to pay for?

Hi, Two Bellies:
   http://www.neihandtools.com/catalog/frame.html

   Old Walt isn't real cheap, but he's likely your best bet.  He keeps  threatening to retire tomorrow, so don't think about it for to long.

Bye
Jack