If I’m not mistaken, the Barnes Expander MZ 195 grain bullet is the same bullet as the Knight 195 grain Red Hot?
The 195 grain Red Hots are available from the Knight website. That’s the only place I’ve seen that bullet available and I’ve looked quite a few times in the last few months.
Edit: I was able to place an order earlier this morning because they showed “in stock” however my order was just cancelled and my money refunded, so apparently they aren’t in stock any longer.