This whole 'gesturing-with-your-gun-to-make-a-point' so often encountered in fanfic and on screen in various tv series has helped remind me once again of the Four Gun Rules we had drilled into us in S.:

1. Every gun is to be considered loaded until a thorough check has proven the opposite to be true.
2. Never point your gun at anything you don't want to shoot.
3. Take your finger from the trigger whenever you are not currently shooting.
4. Be sure of what and where your target is.

And never, ever, do anything with your non-gun hand that involves any movement/clenching of the fingers. It is a fact that often the other hand unconsciously repeats what the first one is doing... ergo, grip a door handle with your left hand and watch a bullet slam into your foot because your right hand mirrored the action and, well, gripped when it shouldn't have. Duh.

So -- any tv cops jumping over cars and opening doors while wielding a loaded gun are just so unrealistic. If you storm a room you'd better have at least two colleagues with you. The first waits with his drawn gun on the wall next to the door. The second has his gun holstered and opens the door, then gets out of the way fast. The third has his gun already drawn, too, and ducks in immediately into the closer corner inside - below the arm of the first officer who scans the room above his trained weapon and yells the famous "Freeze!" in case he encounters a human being. The second one has now also drawn his gun and ducks in next, going to the other corner inside. Both check their corners for danger, and only when they give the all-clear the first officer goes in, and immediately moves out of the open doorway to not make a target out of himself. Then they check the rest of the room and, if there is one, repeat the same actions at the next door.

So, just for the record -- sex play with a gun in a consensual, loving relationship (and by a law enforcement or military officer) depicted in fanfic should better include the fact that both participants have checked the gun first, and made sure that it is unloaded. Otherwise -- unprofessional. Out of character. After all, our protagonists supposedly are not only more than halfway competent in their jobs, but also the good guys. Not counting Alex Krycek et al, of course. *smirk*

And, just for the record, the only (temporarily) safe place to hide behind a car is behind the engine block. Otherwise -- normal bullets punch through, hit you, you're dead. End of story.

Oh, five more things:

Hitting a car's gas tank with a shot is very unlikely due to its location; and even if you're lucky enough to do it, there's no "boom". An explosion happens only on tv so the producers can show off their pyrotechnics. The car just keeps losing gas until the motor stops running.

Hitting a person with a shot never, ever slams the target into the wall or floor behind him. We were told that a colleague of our weapons instructor wore the best bulletproof equipment there is and let himself be shot at with various types of bullets and guns... and he remained standing the whole time. Even in automatic weapon fire. So, say goodbye to that particular urban legend. You remain standing. Perhaps you crumble to the floor if you're hurt and bleeding a lot (or, of course, dead). You don't demolish plaster by going flying like a rag doll. Ever.

Hitting a person with a shot usually means the bullet will remain in your target, and will not go through to hit other people/things -- if you use law enforcement issued ammuntion, that is. Said bullets have a plastic tip that's pushed into the hollow body of the bullet and mushrooms the bullet's body so that its speed is slowed considerably upon entering human flesh. Law enforcement would have lots of lawsuits on their hands if they used other ammuntion and took down innocent people unlucky enough to happen to stand behind a criminal when he's being apprehended. The damage to the target will be more extensive (and the likelyhood of inducing shock in that person will be higher), but that's the price that has to be paid.

Hitting a non-bulletproof windshield with a shot means the bullet goes straight through without shards flying everywhere. The deviation from the trajectory is negligible, too.

And, last but not least, you never, ever use your gun to shatter a glass pane. Plays hell with the delicate inner workings of the mechanism. Law enforement personnel usually have nightsticks which are way better suited for that action. Furthermore, your weapons officer will kill you if you fuck up his baby. Bad, bad idea.