You say mono metal.
I"ll just say if you think any of todays Barnes don't ever or very rarely expand you have not shot them at all.
I've yet to see one NOT expand. There could always be a first, but FAR from what you expound on.
You are mostly alone in your thoughts of Barnes rarely if ever expanding is all I can say.
And if you are on here with yet another name, folks like that I have zero respect for.