A few days ago someone hit me up on Discord to ask a gun question to clarify something for her daughter. I thought I'd answer it here.
The background
Legit steem-user 
I believe two guns were involved in the scene, one with the bullet in it and one not. Something like that.
The question
Would someone picking up the gun know that it had a bullet in it by the weight?
The answer
If one bullet then I would say no they would not be able to pick the difference on simply picking it up. It's doubtful a human could feel the weight of one single bullet that is inside the gun. In the palm of the hand, a single bullet yes, but with the added weight of the gun? I don't believe so.
The test
Unfortunately I have no ammunition for my revolver currently and so the weight test had to be done with one of my semi-auto handguns. The 9mm CZ Shadow 2.
Below you can see the weight of the handgun plus one empty magazine, i.e. no ammunition loaded. 1220 grams.
The second image shows the same gun and magazine with 10 rounds loaded showing the weight of 1410 grams. The difference being 190 grams.
That makes each bullet 19 grams in weight on average.
I shoot a lot and would know instantly if this gun was empty, or if it had 10 rounds loaded. In fact probably with less rounds too...But when I tested it with my wife Faith just now...Well, at 5-6 bullets she wasn't 100% percent sure if it was loaded or not. With 10 in there she could easily tell it was full, or near full by the weight. One single bullet would not be noticable.
Conclusion
This ridiculous game is played with a revolver which allows the cylinder, the part the bullets go into, to spin. It is loaded with a single round and the cylinder is spun around. Once it stops only a close inspection will tell where the bullet is. But if it is in the right location the gun will go bang.
Here's the thing though; Only the one bullet is loaded. Let's assume that bullet is a .38...It means the bullet will weigh roughly the same as the 9mm round used in my test, 19 grams, or maybe a little more. In my opinion though, it would be impossible to tell it was in there by simply picking up the gun. Especially since the person picking up the gun is just about to put it to their head. I would expect some high-emotion in that circumstance, less clarity of thought.
Further to that, even if there were 6 rounds in the gun a person under duress, or not comfortable with guns, may still not tell whether there is rounds in it or not. I mean, how many have hefted a real gun with and without bullets in it? Some for sure, but many more have not.
Anyway, that's my conclusion so I hope this helps
Keep in mind that if I did this test with my CZ P09 (9mm) the result would be different. Because that gun is polymer, and therefore really light, it is much easier to tell what is in it as far as bullets go. Still, with only 3-4 in there I still doubt someone would pick it unless they were really comfortable with the gun.
A note: Playing this stupid game will not work with a semi-auto because when a loaded magazine is inserted the rounds are all on top of one another. Rack the gun (pull the slide back and let it go) and there is a bullet loaded into the chamber each time until the magazine is empty. Everytime the trigger is pulled it will go off.
As a responsible gun owner I have to say that stupidity and complacency around guns and irresponsible handling and use of firearms can only ever lead to something bad. People can, and do, get injured and killed through misuse and idiotic behaviour. A quick search on YouTube will demonstrate that. I'm not sure why cartoons have scenes depicting Russian Roulette in them either, however it's certainly not a legit use of a firearm.
If you're interested here's a video of a firearms instructor being a complete dick. You may have seen it, but watch again...It demonstrates that guns should be treated with a lot of care and respect. See it here. He has done so many things wrong here...And why is the gun even loaded during a demonstration of grip technique? I don't know what happened to him, but hopefully he isn't allowed anywhere near guns again. Ever.
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