just tried my magnet out on trigger of CC. it is metal of some sort, not polymer.

 

Thats a good way to tell. Aluminum is not magnetic. Steel and Iron is. It may be an alloy with some steel or iron if the magnet stuck.

 

I put a magnet to my CC trigger. It stuck. So it's Ferris metal. Appears to be stamped steel.

 

It is not stamped steel. It is a cast/MiM steel part, depending on the production generation..