I understand your question and in my limited experience, at this time in history, just about everything is or has been covered. The only thing I could think of would be some radical weights per caliber, ie.; a 150 grain .45 cal rifle bullet or a 125 gr. .22 cal bullet. Mebbe some exotic bullet materials? Tungston? or Hybrid bullet compositions? Bronze jacketed tungston, jacketed zinc? Or mebbe custom purpose bullets? solid copper .17 cal squill bullets, or 500 gr. tungston expanding bullets for buffalo?. Sorry I can't be of more help...
My Anchor is holding fast!