For the non-navy types:
GM1 = Gunner's Mate 1st Class Petty Officer (E-6)
SK2 = Storekeeper 2nd Class Petty Officer (E-5)
OS2 = Operations Specialist 2nd Class Petty Officer (E-5)
SN = Seaman (E-3)

At one point, I was attached to the base security team. With this assignment came a lot of, let's say interesting training. One such instance involved them making some scenario training videos. They lined 5 of us up beside each other facing a TV on the mess decks. Then they gave us an unloaded gun with the hammer cocked. We would assume a shooting stance and then stand there pointing the gun at the TV.
They would then play a scenario, in first person, on the TV and we had to decide when to pull the trigger, if at all. Then we would re-cock the hammer and go on to the next scenario.

First Scenario

Virtual me is on patrol. I come up to a locked gate and someone has bolt cutters trying to cut the lock. Virtual me yells for them to drop the bolt cutters. They see me and run towards me with the bolt cutters still in hand. Virtual me yells for them to stop and repeats the command to drop the bolt cutters. As virtual me is issuing the 2nd set of commands, real me pulls the trigger. This also causes the four others lined up alongside me to fire their weapon.

The GMs know what happened, but start on the other end of the line to make it obvious to us what has happened.
GM1: "DC1 About2Retire, why did you fire your weapon?"
About2Retire shrugs and with an "I don't give a fuck" attitude responds "Because they did."
GM1: "SK2 Should_Never_Even_Hold_aGun, why did you fire your weapon?"
Gives similar response as About2Retire
They continue down the line in this manner with everyone else admitting that they only shot because I did. Then they get to me.
GM1: "SN Dreble, why did you fire your weapon?"
Dreble: "Well GM1, I had already issued the command for them to drop the bolt cutters once. They were running at me very quickly and those bolt cutters could be used as a weapon to incapacitate me and then they could take my weapon. I would rather that not happen."
GM1: "Let's see what happens."
He un-pauses the video and the person continues to charge. When they get within reach, they swing the bolt cutters at the camera and the screen fades to red with the words "YOU'RE DEAD!" in white letters. They pause the video. They tell us that we made the right call, but pulled the trigger a little too early.

Second Scenario

Virtual me is on patrol. I come up to a door that is supposed to be secure, but it is ajar. Virtual me calls it in over the radio, but then I hear movement, so I open the door further. There is guy about 30 feet away with a box cutter in his hand, blade out. There is a tool bag under a breaker panel and a pry bar on the ground. Virtual me yells for the person to drop the knife and identify himself.
The guy turns to face virtual me. He drops his hand to his side and takes one step towards me. I pull the trigger. This time only SK2 Should_Never_Even_Hold_aGun is the only one to follow suit. They pause the video. Same as before, they question SK2 first and have her admit that again she only pulled the trigger because I did.
GM1 (clearly a little irritated at this point): "So SN Dreble, you felt that him dropping his arms was grounds to shoot him. Why is that?"
Dreble: "Well GM1, he did also take a step towards me. He is very close to me and still holding the knife that virtual me told him to drop. I feel like he could cover the ground between us pretty quickly and then I could get stabbed. I would rather that not happen. Also if I'm being honest, something about him just doesn't feel right"
GM1: "Well, you can't put something about him just doesn't feel right (said in a mocking tone) as justification for shooting when you are filling out the after action report later. Let's see what happens."
He un-pauses the video. After the 1st casual step, the bad guy charges full speed and in about 2 seconds is on top of the camera stabbing away and the same red screen from the first scenario appears letting us know that if we hadn't shot by then, we were dead.
Again, I was chastised for pulling the trigger a little too soon.

Third Scenario

There was a 3rd scenario, that I do not recall what it was. It went down like the 2nd one. I pulled the trigger, causing SK2 to pull the trigger. I was told that I shot too early, then they un-paused the video and if you didn't shoot you died.

Fourth Scenario

I forgot what this scenario was too. I do remember that this one involved approaching a vehicle with someone in it. This time OS2 BigSneeze let's loose with a massive sneeze that makes us all jump, except SK2 Should_Never_Even_Hold_aGun who jumps and also pulls her trigger. No one else fired during this scenario.

Last Scenario

We are warned before the video starts that even though the person on the video looks familiar, for this scenario we do not know the person that we are approaching. Virtual me is on patrol (I bet you didn't see that coming). I'm walking under the pier, next to a ship. There is someone on their knees with a duffle bag beside them. It is the GM1 that is conducting the training. Virtual me approaches virtual GM1 and yells for him to put his hands on his head, turn around and identify himself.
In his typical GM1 "you're being a dumbass" tone, virtual GM1 tells virtual me to shut up and go away. Virtual me repeats my command for him to put his hands on his head and turn around and identify himself.
This causes virtual GM1 to lose his shit. He starts cussing like a sailor. He stands up and puts his hands on his head and then turns to face virtual me. He starts screaming a bunch of shit about how I'm a dumbass and I'm going to ruin everything and just flies off the handle. But he is empty handed, so I let him stand there and yell and cuss. Virtual GM1 takes a step towards virtual me and makes a comment about how he should kick my ass.
So here is where I made the briefest of fuck-ups. When virtual GM1 said he should kick virtual me's ass, real me, smirked and said "I would like to see you fucking try."
As I say this, virtual GM1 stops, turns, and jams his hand in the duffle bag. So real me pulls the trigger. But this time, and for the first time, I'm the only one that shoots. I'm just kidding. SK2 also fired. GM1 pauses the video. He is pissed because he thinks that I have been fucking around and not taking the training seriously. This is when he points out that being trigger happy can cause others to also shoot unnecessarily in high stress situations. He asks SK2 if she is happy with her decision to fire. She says no. Then he asks me if I am happy with my decision. I confirm that I am. He un-pauses the video. Virtual GM1 produces a badge from the duffle bag and aggressively approaches the camera saying that he is a cop. Real GM1 pauses the video and asks me if I think that I would be able to sleep at night knowing that I needlessly killed an undercover cop. My response, "Like a baby."

This gets my ass royally chewed. He goes off about how I haven't taken the training seriously and that I shot early in every scenario and he is thinking of pulling my weapon quals. He went on about how I would have killed a good man just doing his job. Also that I have failed and will have to re-do these scenarios. You know, the exact same ones because that makes sense. I let him finish, without interrupting and then it's my turn to talk. This was years ago, so I don't remember exactly word for word what was said, but I'm going to get us close.

"GM1, I did take this training seriously. Hell, I think that I'm the only one that did. Every scenario started with my gun drawn. When I'm doing my patrols, do I walk around with my gun already in my hands? Do I round each corner and assume the firing position that I was in during the scenarios? Since I do not, that means something else happened in every scenario before the video started to make me draw my weapon. I know my ROE (rules of engagement) when doing patrols. My gun was already out from the start which means that in every one of those scenarios, we started on strike 2. When they didn't listen to the commands that they were given, that was strike 3. Every one of those people not only escalated the situation into deadly force territory causing me to draw my weapon in the first place, but they also failed to follow my orders when I was taking control of the situation.

On top of that, they also went ahead and made movements that could be seen as threatening while having a pissed off person in uniform pointing a gun at them. You mentioned earlier that I can't use "something about him just doesn't feel right" (said in the same mocking tone that he used earlier) as justification to shoot someone when filling out the after action report. Well I promise you that if I ever have to fill out an after action report, at the point that I decide to draw my weapon, I will have my justification to use deadly force right then. At that point, any delay in pulling the trigger will be seen as leniency. In every one of those scenarios, I should have shot the person before the video started.

That also means that Mr. Undercover Cop "that was a good man only doing his job" (using the same mocking tone I used before), already had his chance to produce his badge and identify himself."
When I used the mocking tone, this caused GM1 to try and interrupt, but I cut him off saying that I let him talk and now it's my turn and continued.
"Instead he chose to escalate the situation. Once my weapon was pointed at him, there is no scenario where he didn't end up handcuffed or dead. Period.
Undercover Cop should have followed my commands and wore the bracelets. After I checked his bag, found his badge and confirmed that he was authorized to be there, I would have released him. He would have a story to tell about how the dumbass Seaman handcuffed him and wasted a 1/2 hour of his time while he was undercover. Instead he needlessly escalated a situation not once, but twice and then didn't follow instructions and for that he died. So yeah, his death was needless, but it was his own doing. I wouldn't have lost a wink of sleep."
GM1 didn't have much a response. I don't remember what he said, I remember being fussed at some more and being told that I will be informed on whether or not my weapon quals were going to be pulled and that I was dismissed.

They created new scenarios and re-did the training about 6 months later. This time you were given a gun belt and you had to decide if/when to draw your weapon and then if you needed to shoot or not. I got a perfect score, including being the only one to not fire in a scenario where everyone else that was lined up with me did.