At a local gun show, I saw some Winchester brass 5.56 mm with flat-pointed, red bullets which looked like plastic shot-through with copper flakes.  They were in American Tactical boxes.  The guy selling them said that they were some form of indoor training ammo.  If I had been forced to guess, I would've figured it was some sort of fancy, frangible bullet.  I should have bought some, just 'cuz.  Does anyone have any info on this stuff?