These are completely plastic. There is a steel insert at the base but it is encased in plastic. When I was shooting trap, a couple of guys fooled around with these. They reloaded just like a regular shotgun shell but they really had nothing to offer over normal shotgun shells.
This is a polymer 50 BMG round. It is a training round that is used in a M2. The normal bolt and recoil spring are replaced with a special bolt. They are fairly accurate out to around 100 yards. Their purpose is to have an under power round to train in places where there is not enough room for a regular range. As you can tell by the red tip, it is also a tracer. Visually, he case isn't much different from the True Velocity case except for the bullet. I've also seen them in 5.56 but I don't have one. The headstamp is 1988.