Was going through some old ammo and found some 357 WW Silver Tips. They had what looked like yellow plastic in the cavity. Had to be factory, I have never loaded silvertips. Anyone come across these? Also found a RP 38hp with the cavity filled with something red. I have one. I kinda remember they are factory something. Not sure if they explode.

They are probably the old "exploder" type ammo, either Bingham Exploder, Velet or Velex brands.