Hey there,
The max really hasn't become extinct. However, it's not that popular from a mainstream sense. It got a bad reputation for flame cutting of the topstrap on the Ruger revolvers it was introduced in. Soon after, Ruger discontinued it. It's loaded I think to something like 52,000 CUP or therabouts. That's quite high for a revolver round. The Dan Wesson revolver had the capability to adjust the barrel/cylinder gap so I think it wasn't too much of a problem there.
Speaking about Contender pistols, I'd say it is still in general use at least for the hunting end. Has a good amount of power in a 10" or 12" barrel for hunting. I like the 35 Rem in this application though.
As far as Sillouhettas Metallicas, I'm not sure as to what degree of use it is seeing these days. Perhaps someone in this game can relate more info on it.
You'll find a lot of calibers that are supposed to be dead, maintain a small but loyal following of dedicated fans. At one time the 444 Marlin was supposed to be dead but as you can see here, it is alive and well. That's what makes this all fun.
