This is Lehigh Defense’s “Maximum Expansion” machined all-copper self-defense ammo aka “Scary-Ass Shit Right Here” ammo. They make it in a handful of popular calibers.
In .38 SPL it makes a respectable ~250 foot-pounds of energy out of a Ruger LCR although with that kind of expansion it falls a bit short of penetration. You can be damn sure all that energy was transferred to the target, though.
It’s a bit similar to the Grizzly Xtreme ammo introduced a while back.
“As I mentioned on the video, the Maximum Expansion moniker is well deserved.
“As we observed in previous tests with Lehigh Maximum Expansion, you can expect best in class expansion with expansion ratios exceeding twice starting diameter. The performance through the 4 layers of heavy weight denim was really extraordinary as this barrier will typically adversely impact expansion.
“We had no problem meeting the 1050 feet per second muzzle velocity in the 1.875″ Ruger, with several test shots exceeding that muzzle velocity by a significant margin.”