@Athos_131: I know you're ignoring me, but I'm still going to give you ammo in this fight.
The best argument against a self proclaimed GGwaG on the internet is the Minute of Angle test. Just ask them to brag about their shot groups at 200 yards.
A minute of angle is 2" at 200 yards. (The Zero point, where the trajectory stops going up, and then starts going down, in a parabolic curve) A gun nut, that's never zeroed his rifle, will brag about a "Sub MoA" gun he doesn't own. I've seen claimed shot groups, with a pistol, as small as 6 seconds of angle. 1/10 of a minute, which is not just impossible, but With A Pistol. Even if you can get that with it clamped into a vice (Called a Bench Rest) your heartbeat will shake it off the mark just holding it in your hand. There's no such thing as a Minute of Angle pistol, because the human arm is not capable of that level of accuracy.
That's why most cops miss, in the kind of firefight they obstensibly train for (Depends on the agency. Marines call the FBI "Accountants with guns" because they count hits to the frame holding the target as "Hits.") They primarily carry, and fire handguns, which quite honestly, are not capable of that level of accuracy, unless it's clamped into a vice.
The only way a Rifle is, is with the stock in your shoulder, 2 hands on it, and preferably laying out prone on the ground, to hold it steady enough. With a bipod, to add 2 more points of stability. (The arms are the 3rd leg of the Tripod.) Unless you have that level of stability, and a target as static as a paper clamped to a bullet trap, anything more than 5 Minutes of Angle is more accuracy than the Shooter is capable of.
If they don't know that, they're not a Goodguy with a Gun. They're an idiot with a keyboard.