In all honesty, when ranges start getting out beyond a couple hundred meters, most players don't *need* to know exactly what they are... and I certainly don't keep track of the exact numbers. The question simply becomes "is he in range or not?" I'm certainly not going to put a ledge overlooking the target's camp exactly 1520 meters away and laugh at people... I'll just say "yeah, you're about a klick and a half out... yeah, you're in sniping rifle range if you REALLY want to try..."
Longest shot I think anyone's ever taken in my game was about 350 meters with a sport rifle. I'm sure a couple of our vehicular combats/drone gun platforms have engaged at further than that (and I know for a fact the mortar one player had in their trunk and guided into the target with the laser designator on their MP5-TX was fired from a few blocks over), but for our games, you've rapidly entered the realm of "who cares exactly how far it is?"
If I had a sniper character in the game, I'd likely make up a 4-significant-figure distance to the target from where he was trying to make the shot... and the number that would be chosen would be either an "in range" or "blatantly out of range" number. Makes life easier
Back in SR3, the DeMarcos used to run a bolt-action assault cannon with an extended barrel for really, really long shots. I'm kind of sad that they've got the same range as sniper rifles now.