.357 mag Omnishock cutaways from the mid 80's, before all the Brady laws.  These first started off as stainless steel screws placed into a wad cutter and a copper gas check added (those are the sectioned ones).  When the AP laws changed, the company started to use aluminum screws (that's the box pictured).  Clever idea at the wrong time, and never really took off.  Word around the block is that the original owner is thinking of getting back into business making ammo again.  (Most likely won't be these)
wolfganggross

Very interesting!

Designed for maximum expansion?  Ive heard about mercury in the same place held in by wax.
It is a .357 though so it is going to mushroom pretty well unless you are using FMJ bullets.