I have heard things like this before, even saw high speed impact footage comparing Bioval to other BBs which confirmed this.See the bioval bbs are frowned apon over here in the uk and alot of european contrys.
Im not sure about how the rest are made but the .27g bbmax ones are made from a different material than normal bbs. This results in better preformance due to tolerences but they also dont deform on impact to dispense the energy. Even is 350 rifles they will break glass.
I also beleave BBB made versions like this but at least they state they shouldnt be used in game.