A few days ago I was talking to a state trooper at work. Several years ago when he worked for for the police department he was shot in the chest. .40 fmj bullet entered about 1" above his heart and exited somewhere around his lower back. I know that this is common among people that have been shot, but it made an impression on me considering how close it was to being a near fatal shot.

I got to thinking that most dead deer I have seen always appeared to have a pretty straight trajectory from entry to exit. I think I have an idea why, but would like to hear someone else's take that is smarter than me on the subject.

I shot a doe that was pretty much broadside with a 180gr 30/06 in the shoulder and the bullet exited by her ear. Pretty strange.

I would be willing to guess a high powered rifle is a lot less likely to do this than a pistol caliber, but it happens.

There are a lot of factors involved. Sectional density plays a large role, but with expansion a bullets SD will change. Pistol bullets typically have a very low SD. African professional hunters have known for decades there is an optimum speed for deep penetration on big dangerous game, and high SD bullets with little or no expansion are the rule. They believe the optimum speed for these bullets is around 2200 to 2500 fps for straight tracking through bone and heavy tissue. Much faster and bullets tend to divert off track when hitting heavy bone more often. This knowledge has been earned through decades of evaluating dead animals and seeing the deadly results (for the hunter) when they think their souped up speed gun is the better choice to go after animals which can claw, stomp or chew you into little pieces.

In my completely uneducated opinion on the matter, I’d say that with a faster bullets with a typically smaller diameter, that it would contribute to the lesser deviation in flight path.

Several years ago I shot a broadside buck at about 60 yards with a .270 Winchester Ballistic Tip. I hit him at the point of the shoulder and the biggest part of the bullet came out just behind the deer's jaw. Last time I ever shot one of those bullets.

Bullets designed for expansion would have a tendency to tumble, versus a full metal jacket that would have a tendency to deflect and be more apt to pressure differences in materials that its traveling through.

The shape of a bullets nose is a factor. Flat nose bullets tend to track straighter than round nose, which track better than Spitzer bullets, all other factors being equal. The right combination of speed, spin, shape, SD and bullet construction are all factors in tracking a straight path through a body.

Slightly off topic, but remember back when the AR rifles were still kind of new and venerated, and uneducated people would propagate the rumor that the 5.56 AR rounds "tumbled" through the air and that's why they were so deadly?

They can, but not always, tumble when they enter the body. IF they tumble, they can create a large wound channel, otherwise they will pencil through. A 55 gr. .223 FMJ has a low SD of .157 compared to a 140 gr 7mm or 168 gr .308 with a .248 SD.

I remember shooting tracers in the army and watching bullets do some crazy stuff. I've seen one them hit the target, buzz around of the ground, and take off again. No joke.

As you stated, I believe that it WAS a rumor promoted by the anti Vietnam media and perpetuated. However, just grazing a bamboo shoot could cause the lightweight bullet to tumble/wobble.

As far as the OP's question. There are way too many variables, caliber, grain, angle, shot location, etc.

I heard many a Medic that had severed in Nam talk about how a 223 will tumble thru a body, after impact. Not during flight. Propaganda? LMAO Yes, tracers do crazy things, many bullets do. You can't see the actions of plain FMJ rounds.

Shooting an M-60 at night with a belt of full tracers taught me that a bullet will do dang near anything when it impacts.

If you shoot a 90grain .223 projectile from a 1:12" twist barrel it will definitely "tumble" through flight

The human/wildlife body does not react the same as ballistic gel. It’s difficult to predict what will happen after the shot is fired. Aim for the correct shot placements and hope for the best. Or use a 50 cal.

I've attended autopsies of murder victims shot by a .22 and the bullet bounced around so much their insides looked like they were shot about 5 times. On one in particular the Doc doing the autopsy commented on that being the reason he would rather be shot by a large caliber than a 22 if he had to be shot. I think he was exaggerating, but his point was made.

It's hard for me to fathom this internal bouncing effect. It sounds more like bullet fragmentation and redirection to me.

Got shoot with a 22lr in my right shoulder and it stop 1/2 inch from my heart still in too this day hurt like a bitch.

Bounce is not a very good word for it. Your description of fragmenting and redirecting is better since bouncing would imply a 180 degree change. Bounce is what the internal parts look like though. Bouncing several times in fact.