That's one of them weird German bullets. Can't remember the name.
Looked like they were shooting aluminum, cerrosafe, or solder for the metal.
At close range, a 308 hunting bullet of most any variety will penetrate 3/8 plate steel easily. The holes look almost like they were die cut. My brother had made a spinner target for 22's out of 3/8 plate stainless. At 50 yds 308 ballistic silver tips zipped right through. Brother was not happy, but he did a filet weld on it good as new.
I was shooting 150 gr XLT's (MV 2750) at an 30 degree angle 1/2" plate at 100 yds and they nearly went through. My father thought it was an adequate back stop . In front of the plate is 1.5 inches of treated plywood.
I believe the metal they were shooting was probably just plain old steel plate.
Now if I could get a hold of some 1" aluminum plate, that might be exciting.