Be dead on the spot with a VMax, I know that for a fact. Bit difficult to walk around with a burst jugular vein...
Bullets are supposed to make up for inopportune placement, immediate fragmentation/expansion and large temporary cavities (which some may wish to call 'shock') helps. All lacking with copper.
I'll be the first to admit that placement was not optimum, not wishing to use terrain and a high level of ground cover as an excuse.
Then again I have not had the fortune of honing my skills over the many miles of open, flat, tilled fields, and tall hedgerows which make up much of the Englandshire recreational stalking scene