That's just a piece of whatever stainless being used as a gong v. target steel like AR550 right? Used to shoot homemade 'gongs' and penetration was way more impacted by the material than the bullet / load v. 180 grain bonded from a .300 at 100 yards doesn't really seem to dent AR550 of sufficient thickness.
You are correct. It's not made for shooting. It's a piece of industrial scrap. The bell end of a heavy stainless pipe. I'm sure it is somewhat brittle. Still pretty impressive. Impact velocity on that hit should have been apx 2,300fps.