I'll try to explain the penetration... I'm a fishbowl thinker so I drift.. sorry!
steel: it's got some flexion to it, although there are MANY types of steel, you're probably going to be shooting low-grade and not thoroughly heat-treated so it's just purified iron. metal is tough but not immeasurably so, it has inconsistent grain and flexion (anomalies that will allow it to separate if stressed-like wood splitting) and if pushed much past what is simply repelled- the force will skip the flexion and deformation altogether and just break right through. metal has flexion to it but can have a grain structure congruent with casting, forging, etcetera. and a flat plate will have a grain going parallel with the surface/flat. a plate is gonna have a flat profile which means most of the mass is just surface area (it doesn't matter how big the plate is, it's just a quarter inch thick- the bullet is probably longer than that). the pointy bullets have sectional density behind a sharp/spitzer contact point to amplify all force on that point and force it through... and as the projectile tapers it will push the hole out to let in more bullet. lots of velocity behind a little mass will "read" high kinetic energy but mass controls inertia and more mass is harder to stop... so a big bullet will still penetrate on through at a low velocity better than a little one (the little one can have more energy but upon striking it won't carry on through but dump the energy as the projectile is "caught")
let's think extremes- 12ga vs 22-250. the 12ga has much more drag due to an aerodynamic nightmare of a shape, and it is bigger. the weight pulls it down faster but that's also what allows it to smash on through tissue. also that big projectile with more drag has that same problem with tissue, it catches matter (flesh not air after entering an animal for example) and will "catch" the tissue (or vice-versa, actually both) and the energy is dumped even though the projectile had great inertia. the drag ruins the external ballistic "ray" but also makes it so lethal by brute force. the 22-250 has insane velocity but little mass, so while it reads "hot" it will not penetrate heavy/dense material very well. it'll dump all that energy really quick when it's "caught" though, so it's great for small game (or people) but not for a huge animal because that flesh will decelerate the bullet (dumping the energy upon entry but stopping the penetration and actual damage to deeper internal organs). the huge energy dump is great for rediculous damage to a a shallow target but not for a deeper one. penetration allows a bullet to go deep and make it to the internals in an animal. while the damage isn't as dramatic at any one point- it is going to continue all the way through the animal assuming that the round had enough "uumph" to get the job done. also, a hole in the chest cavity will depressureize the lungs, cause edema, dry out the membranes surrounding the lungs and cause pulmonary failure fairly quickly. heart shots are obviously fatal but not immediately by virtue of destroying the heart (the animal still has some energy and time to run off). "shock value" is not a definiteive term but for it to be effective it's got to hit spine, neck or brain to immediately sever all mobility to allow a "stopping" shot to work. the only thing that will instantly disable is nerve damage, instant death is only capable with a brain shot. while nerves may incidentally be targeted/injured with shrapnel, hydrostatic shock, wound temporary cavitation and such, only the nerve damage actually causes the animal to drop right there.
you have to be a nut and read this stuff lots to grasp it all at once. my advice is to read up on as much of the fbi shooting data as you can stand. also the cadaver and live animal tests that led the army to adopt the 1911.... thompson lagarde maybe?
