Many years ago, I had a friend who had 20 or 30 boxes of 45 acp he had taken in as part of a very large purchase of guns, etc. There were 20 or 25 rds to a box. The boxes were dark green cardboard, absolutely square, and the corners of the boxes were reinforced with perforated metal strips. The 'lids' folded back.
The bullets looked like normal hardball except that they were very dark brass (bronze?) colored.
At his range, I loaded my Commander magazine and proceeded to fire at a monstrous dead tree about 20 yards away. (It was safe - it was on his farm and I was shooting downhill into a tree-choked swale.) I noticed the 'tightness' of the report immediately. The fired case flew about 30 feet behind me and struck the windshield of my Corvair and then ricocheted about another 30 feet! I could feel the pistol's slide recoil, slam to a stop then slam closed as never before! Needless to say, I fired no more of those rounds and some time later a cartridge collector told me it sounded like I had fired sub-machine gun ammunition.
I want to say the writing on the inside of the boxes' lids was French. (I won't shoot much of anything I don't reload myself anymore