For instance, consider range modifiers. Currently, they're a 0/-1/-3/-6 to your dice pool. With a high dice pool, this wouldn't make a ton of difference and doesn't really represent what's going on - what's going on is not that you're less skilled, it's that the the weapon just isn't accurate at that kind of range
I disagree. I can group a lot closer at 50 yards than I can at 100, but it's not the rifle's fault, it's mine. A small problem with shooting stance, or site picture, or jerking instead of pulling the trigger will make a more substantive difference the further out in range the target is, and a good shooter knows how to minimize or eliminate those mistakes.
By imposing Limit modifiers to shooting tests, you're saying that someone shooting an Ares Alpha at Extreme Range with 9 dice in their pool is on average, as good a shot as someone with 18. Now, 9 dice isn't unskilled, but it does not represent the same kind of dedication, and training, and ware, and magic that gets somebody to the super-human level where they can reliably pull off 4 hits at 550 meters, which would seem to me to be within the capabilities of that kind of rifle -- maybe someone more knowledgeable than myself will chime in on that.
Well, I can tell you that a 9mm round has enough energy to fly approximately 3km. That is not to say you could HIT something at that range.... just that the round has the potential to travel that far.
The 2 biggest factors to accuracy of a weapon are gravity and windage. Bullets do not travel in a straight line, they arc through the air. Take a standard .308 hunting rifle, and zero it in for a 400m shot, at the 200m mark the round will land 2-3 inches higher then center. At 600m the round would be 3-5 inches lower.
Windage is a factor just because it blows the bullet off course causing it to sway in the direction its blowing.
This is why snipers use a logbook. It contains all the info and formulae needed to correct for these issues. They litterally look up/work out the firing adjustments they need to make. (Target is 600m away. Wind speed is 11km/h from the left. I am using 'X' weapon.... I have to adjust my sights 3.25 inches up, and 1.75 inches left.)
Technology has played a part in fixing sone of these challenges. Rifled barrels to put a spin of the bullet to decrease windage. Longer barrels to increase velocity. Adjustable sights made to the ballistic performance of the weapon...
And, its important to point out, not all weapons are created equal, even amoung the same calibers. The remington model 700/.308 is so accurate that it is used by many police agencies as a sniper rifle, even though it is classified as a hunting rifle. (And really, really more accurate then other .308 hunting rifles....)
Actual sniper platforms push this accuracy even farther through the use of finely balanced weights and forces...
And yes, there are some people out there that are ungodly accurate with their weapons! I forget the guys name, but there is a Yank out there that can hit a small balloon at 60m with a snubbed nosed .38 (accurate to 20m) on the first shot.... that's 3 times the "accepted accurate range" of the weapon!