is when an author you thought knew better throws in something that is absolute bullshit. Often involving firearms.
Some of the Longmire books have this, and I'm told the tv series does as well, for instance. But my prize-winning choice is L. Sprague de Camp* in some short stories collected in a book called Rivers of Time. Rivers is longtime hunter who, due to the invention of a time machine, takes people on safaris to hunt dinosaurs. So far so good.
Then comes the mess: 'My clients must be able to shoot a .600 Nitro Express, because that's the only rifle capable of actually knocking a dinosaur down, so it is the only rifle that makes it safe enough to hunt them.'
If you're one of the folks who comes through here occasionally who doesn't know much about firearms, you may be wondering why that bothers me so much. Short version: Firearms Do Not Work That Way. Period. And claiming they do means he either doesn't know what he's writing about, or he's writing this crap because it sounds good and screw facts.
Give you an example: Winchester makes a load for .45-70 that fires a 300-grain bullet at about 1800 feet per second as it leaves the muzzle; that works out to that bullet carrying 2355 foot-pounds of energy. That's a serious amount of energy. It's advertised as being for hunting deer and elk. I've seen numerous accounts of people hitting deer with it, and the result is either the deer falls down dead, or takes a few steps and falls over. Same thing with bear; it does not physically knock them down.
So let's play with numbers: say you've got a big whitetail dear that weighs about 150 pounds. That bullet, at 100 yards, still carries 1545 foot-pounds which is ten times the weight of the deer. Normal result: bullet often penetrates completely, animal makes a few steps(at most with a good shot) and falls over.
Now let's look at that .600 Nitro: a .60-caliber 900-grain bullet moving ~2000 feet per second, so about 7600 foot-pounds(I'm averaging this by the data I found); it's a monster of a cartridge, with recoil to match. Now, let's say we've spotted a average size Tyrannosaur, which weighs roughly 9 tons, or 18,000 pounds. Say the beast is close enough that the bullet is at full velocity when it hits. The T-rex weight is 2.36 times the muzzle energy of the cartridge, and it's a solid bullet, non-expanding, designed to be able to penetrate deeply enough that it can go through heavy skin, muscle, and bone to reach the vitals. The .600 cannot knock down a five-ton elephant, but it's supposed to magically knock down a dinosaur weighing close to two times as much?
Now, it being something you carry and shoot and not a artillery piece with a carriage, the recoil is going to be horrendous, making it very uncomfortable to shoot. Not many people have used it because of that and the expense of the ammunition. Most people go with something less powerful but still capable of penetrating to the vitals, such as(one I'd love to own) a .470 Nitro Express. That's a 500-grain bullet at about 2100 fps, about 5100 foot-pounds at the muzzle, and if you place the shot where it needs to go it'll kill anything. And, just like the .600, it cannot knock a large animal down. And it doesn't have to to kill it. Just like self-defense, shot placement on something large and dangerous is The Key; you cannot carry something powerful enough to stop an attack if you miss anything vital**.
So that's my bitch about Things that ruin Books and Shows for the night.
*I was pissed at him already for his editing of many of the Conan stories.
*Shut up. I know, but this is still the basic fact we have to work with: to stop animal or man, you have to hit something vital.