Not sure if the pic will show up in full size but...
I decided to conduct a test on which guns had which range. I made a simple map, very long with markers at each grid. At one end there was an ammo crate. When you're on your last clip, an icon will appear to guide you to the nearest ammo crate. When you look toward the ammo crate, it will also show how many meters away it is. I used this to find out certain distances by having a second player (borrowed a friend's PS3) stand next to the crate while I back away. When the crosshairs no longer turn red when you aim at a player, you're out of range. Of course the excludes funky-firing weapons like rocket launchers that can be firing at an angle for more distance.
I also found that each grid in the mapmaker is 64 meters by 64 meters.
All of these were double checked so there shouldn't be any errors.
Random crazy junk like this is what I do in my free time.

I found it interesting that the M1903 had more range than the SVD and Dart Rifle.
What really bugged me was that the G3-KA4 had more range than the AK-47 even though the AK is listed as having more range...
Also take note that the M-249 SAW is the longest range weapon short of a sniper rifle.

I do love that the Flamethrower can only hit at 7 meters or less. ROFL!!