The only thing I can figure is that friction has something to do with it. That fast bullet must hit with such force that melts of softens the steel much as a shaped charge would do.

That... or perhaps its just like trying to throw a pencil through a sheet of notebook paper... have someone hold just the top, and the pencil will fall to the floor... the paper gives way... have someone hold the top and the bottom... pencil will go through even sideways.... the tighter you pull the paper... the easier it is for the pencil to make it through.

So it may be with steel and fast bullets.... steel has a great resistance, but when it comes to a certain point with speedy bullets, the tougher the target and the more the resistance... the better they work.

But looking at it as such... its a great varmint round, but don't expect it to work that way on bigger game... whitetail size and up.