I recovered a bullet fired from my AR 15 two weeks ago after it skipped across some snow down range of my cardboard target. This bullet was a 40gr .224 Nosler Varmageddon. I could load it again if I wanted. You can see where the plastic tip has bulged slightly at the point of contact with the copper jacket. Almost to the point of upsetting/expanding the copper jacket. But not quite. A soft enough landing in the snow that it survived its hop-skipping landing intact.
The only wear contact on the bullet between the engraved rifling is midway between the lands - center-line of the grooves. The same as the wear marks down the grooves of your bore.
I've recovered bullets fired across ice covered lakes before also. It's remarkable how well a stabilized bullet will continue to track point forward while skipping off the ice several times before eventually coming to a stop. A hunting buddy of mine once took a long shot at a timber wolf that was crossing the ice on a large remotely located lake. Was shooting a 300WM. This was in the days before laser range finders. He had no idea how far out the wolf was. The wolf dropped at the shot, but regained his feet and made it into the adjacent wooded upland area. I showed up after the fact and after walking out to where there was some blood (where the wolf was hit), saw it was quite a long shot indeed. My buddy was sure he'd just made the best shot of his life!
I used to sight my rifles in for around a 375yd point of impact in those days, so I knew a little about longer range bullet trajectory. I asked my buddy how far over the wolf's back he'd held and knew there was no way the bullet hit the wolf in flight. So I walked back from the POI toward the shooting position - about 625yds away. Around 80yds from the point of impact, I saw a bullet groove mark scored into the surface of the ice - .308 caliber width. But that was still too far for the first bullet impact. I walked another ~100yds and found another bullet score mark in the ice. Turned out he'd hit this large timber wolf on the second bounce. The bullet score marks were both 0.308" width, appeared to be point forward, and the bullet tracked in a straight line until it skipped into the wolf after the second bounce. Took some of the polish off the best shot of my life comment. Was good for quite a few giggles.
The bullet set just to the right in the photo is the nose of a Nosler 55gr .224 Varmageddon. I included it in the photo for the trivia minded. The plastic tip was installed in the nose of the bullet backwards from the factory. So much for the beneficial application of artificial intelligence on the production line!
Makes me wonder about the automobiles that are being marketed to pilot themselves down our roads and highways.