Your jacketed Hollow point performed as advertised. You did not indicate the distance from you to the deer at the shot, but If you were shooting that bullet at that velocity at any range under 50 yards, I am amazed that the bullet stayed together after taking out that vertebrae. If the bullet had been going at a slower velocity, it probably would have exited the deer's neck.
With soft lead, the lead flows, slowly, (unless its hollowpointed), giving time for much greater penetration( due to the heavy weight of the bullet or ball) Remember, the bullet or ball is spinning out of a rifle, so that it going through flesh and bone like a high speed drill. Out of a smoothbore, the ball will not spin, or rotate, as there was nothing in the barrel to cause it to rotate.
On your rifle bullet, the bullet was not only affected by high velocity, but it also was spinning fast, and that is the force the bullet-maker relies on to cause the Hollow Point Jacket to open up quickly, slowing the forward motion of the bullet, and expanding the bullet to transfer more energy to the game. A secondary result of these changes is that the bullet slows when it hits bone or hard tissues, as if someone hit the BRAKES.
Compare your observations to my own as a kid. We fired a .45-70 405 grain cast bullet into an elmwood stump at about 10 feet. Velocity was about 1200 fps. The bullet was cast, round nosed. It traveled through about 13 inches of tough wood, never expanding, but losing lead off the nose and sides of the bullet. The bullet we dug out of the stump was .43 caliber, and about an 1/8" shorter. You could still clearly see the grease grooves, although no grease was left in the grooves, and they were very shallow markings on the smaller diameter bullet.
If I shot that same bullet today, out of my Marlin, at a much higher velocity, even it would expand, although not as much as a hollowpoint bullet, cast, or jacketed. I have a mold for the old Lyman 330 grain HP Gould design bullet, just for loading up rounds for deer sized game. Its basically the company's 350 grain bullet, with a long hollow point hole in the top. It does expand in flesh. The 350 grain model makes a great Elk bullet, because it does not expand as much, if at all, at the ranges where Elk are often taken. It shoots a lot flatter than the heavier bullets, tho'.
I hope that helps you understand these differences. One of the problems people have with shooting MLers for hunting, is that, like most of us, you start shooting and hunting with modern cartridge guns, shooting jacketed bullets. You have not read the literature about how the early jacketed bullets performed so poorly, not expanding when they were suppose to. You live in and era when the bullet makers are now producing jacketed bullets that do amazing things over a wide range of velocities.
It was not always that way. In the early days, the manufacturers were trying to deliver the same performance hunters were used to getting from the CAST bullets, and pure lead balls.
Shooting a SMOOTHBORE with a pure lead ball, then, just doesn't seem to be the right thing to do. If you have been poisoned by some of the naysayers- Toby Bridges is the worst-- about RBs effectiveness, and have no personal experience, you come to this sport thinking we must be out of our minds, or are a cruel and heartless bunch of bloodthirsty torturers to be hunting deer with cast RBs.
The pure lead ball( and pure lead cast " shotgun " slugs) DOES expand in flesh, does transfer shock and energy to the game, and is responsible for many one shot, drop-them-in-their-tracks kills, when the hunter accurately places the ball in the heart/lung area of a deer's body. And IT DOES IT AT MUCH LOWER VELOCITIES than can a jacketed hollow point. Some modern hunters used high velocity jacketed bullets believing that hitting a deer anywhere will result in a quick kill. We know better, and pick our shots. We don't have 3-5 back up shots to spray at a deer. And because we shoot guns with traditional open sights, we expect to have to take shots that are closer than 100 yards, where we can be accurate with those sights. With Smoothbores, we prefer to pick shots at ranges under 50 yards. That is far less than these guns can sometimes hit a deer-sized target, with the right loads, and way short of the ball's effective range to kill game.
I load and shoot jacketed hollow points for my handguns for " social " purposes, and I know what velocity they need to be traveling to expand, and I know that at certain ranges, the bullet will cease to expand predictably, and bullet placement becomes everything. Because I am not choosing to hunt game with these loads, but merely use them for self-defense, I am not concerned about the bullet performance at longer ranges. I can still hit people at distances others consider " rifle " range, with my handguns. ( All it takes is practice). :hatsoff: