tiriaq, I'm glad you brought that up. Just this week, a young friend emailed me some pics of 7.62x39 bullets that were ground back to the cores.
There was a time in the late fifties and sixties when it wasn't an uncommon practise. There were even a few businesses that marketed them.
They were about 1/3 the price of comparable commercial loadings.
They usually gave poor accuracy, wouldn't expand reliably and in several instances would separate from the jacket on the way to the target. I have an acquaintance that has a crate of milsurp he picked up 35 years ago. He is rather tight with his pennies and figured it should outlast him. He regularly grinds the tips back to the cores. He also wounds a lot of game. As I said, he's an acquaintance not a friend.
On the other note mentioned, it seemed like a good idea when I was younger and poorer to follow this practise. I was playing around with pulling the bullets, grinding them in a jig for conformity and reloading them in boxer primed cases. I never could get them to shoot acceptably and I shot hundreds of them, that's where I noticed that they would separate. The last one I shot, separated in the bore. It felt and sounded a little strange, so I checked the bore and sure enough it was blocked. I pushed out a jacket. It was one of those that had an open base, exposing the core. With a solid base, there may not have been a problem.