Royas and 666th: It is an interesting question here - is it muscle memory, or middle brain training (or are they both one and the same)? There's an example that got cut early on in the pre-final draft stage before I sent it in to the Escapist for their editor to have his go (the first draft was around 2,500 words, the final draft I handed in was around 2,000 words, and the published article was around 1,500 words - that being said, the first draft had a lot of fluff, and the shorter lengths were a great improvement). Basically, it was about calling 911.
There's this old dumb [insert stereotype here] joke that goes "What's the number for 911?" When I was reading up on combat stress, I found out that the joke is actually a reality quite often, and with very smart people. What happens is that somebody gets seriously hurt, the person next to them's body goes into "survival mode" from the stress, the logical brain shuts down, and the mammalian brain doesn't know how to dial 911. So, it's very important to spend a bit of time practicing dialing 911 on a de-activated telephone, just so that you know how to do it. I really hated leaving that part out, particularly since it's advice that could save a life or two. Unfortunately, there was no way to add it back in and still have the paragraphs flow properly.
That being said, I think you're both right that there's no way a violent video game of any sort can teach you how to use a gun. You've got to pick it up and use it. I've heard some rumours that playing first person shooters can increase one's accuracy when shooting once you do know how to fire a gun, but I've never heard of anybody putting it to the test, so that one has to count under the "unverified rumour" category. I've played a few FPS games, and I can barely hit the side of a barn without a properly ranged telescopic sight. Now, I'm no fanatic when it comes to FPSes, so perhaps I didn't get something that a more regular player might have, but my own experiences didn't really support the improved marksmanship idea.
You're absolutely right, Royas, about what firing a gun is like for the very first time. What led me to writing this article was research about my great grandfather, who served in the Imperial Russian cavalry in WW1. I'm trying to write a book reconstructing his experiences, so I was researching how people react under combat stress (hence Grossman's On Combat), and I wanted to know what it was like to fire the sort of rifle my great grandfather would have fired. Happily, one of my military friends has a WW1 Mosin Nagant carbine rifle, and he was kind enough to let me try firing a few shots out of it. Another military friend was kind enough to let me learn how to fire a rifle in the first place with his .22.
For those reading this post who don't know anything about rifles, a .22, from what I understand, has trouble doing any damage after about 150 meters (please don't take my word for that, though). A Mosin Nagant, on the other hand, can blow somebody's head off at 1,500 meters. So, my only previous experience being a .22, my friend with the Nagant warned me that it was going to have a lot of kick, and it was very loud. I lined up the target, and pulled the trigger.
The loudest sound in the universe went off beside my head while at the same time the rifle butt decided that it really wanted to be about three feet behind me, and my shoulder was a minor technicality. My friends were laughing at the look on my face for about five solid minutes. It was actually a bit surprising, though, just how fast I got used to it. By the time we did some tactical shooting (the paper silhouette barbed wire guy had a really bad day, although we had to work to make that happen), it wasn't bad at all.
Really, I think the military conditioning argument can't be extended beyond mindset, and even there, it can't be extended beyond mindset in similar circumstances to the game you're playing. I don't think there's any way you can convincingly argue that it would do anything more than make it more acceptable to your middle brain to pull the trigger on another human being when you're fighting for your life. Anything past that has to be a stretch.
(On a personal note, I really do hope that in the end, some researcher somewhere is able to provide good, solid evidence that the conditioning argument from my article is wrong. Even if it is just conditioning that could only kick in once one is in a life or death crisis, and even if that might also make us mentally harder to victimize, the thought that we have been partially brainwashed by accident is a really horrifying one.)