you read a lot about DRT, it happens a lot, most of the time when the bullet completely uses its energy inside the deer. some say its from hydrostatic shock, some say hydraulic shock, its actually a combination of both. a bullet that is designed to work best, (mushroom and penetrate), at 2800 fps, slams into a deer at its point of most resistance(middle of the shoulder bone) @ 3000 fps, immediately fragmenting and creating a massive wound channel, since deer is mostly water other than bone, the water is displaced by the shock wave created by the bullet, bad things happen to the deer at this point.
Blood is suddenly and violently pumped both directions from the point of impact through the major blood vessels (hydraulic), the lungs collapse (hydrostatic), the intestines are compressed, all the while that massive shockwave is traveling both directions from POI till it hits the central nervous system (the brainstem) this overwhelms the entire system causing an emergency shutdown of everything (yep it ruins their day). the deer is still alive at this point but expires before the systems are restarted, it works, no tracking but ruins meat like no other shot.
the head/neck shooting has the same effect but the deer dies instantly and doesn't bleed out internally as well.
this is my opinion after over 40 years of deer hunting in a target rich environment
RR