Kilometer range shots present a number of problems to the shooter. Primarily, even the highest velocity projectiles will have at least several seconds of flight time, greatly limiting their use against moving targets. Additionally, the longer the flight time, the more the projectile will be influenced by wind. Long-guns almost always use homing rounds to overcome these problems, and come with special optics and smartgun systems suited to guiding rounds towards moving targets from greater than usual distances.
There are other problems. Each shot exhausts large capacitors and coolant tanks, making them resource hungry. Long-guns can be disassembled for transportation, but even then are hardly man-portable, breaking into five ~25kg pieces. They are therefore only used for shots that can be planned well in advance, or are built into fortifications. Many military bases have camouflaged bunkers set kilometers away, positioned to fire on attackers from unexpected angles.
Several military contractors and hypercorps are designing vehicles that will serve as long-gun platforms. A mobile driving or flying long-gun would be very difficult to defend against, as it will have re-positioned by the time any shot can be traced back.
Long-guns are wielded with the Kinetic Weapons or Gunnery skills.
Long-Gun [Expensive] DV: 3d10 + 10 DV Average: 26 AP: -25
Ranges: Short 1km Medium 5km Long 10km Extreme 15km
All long-gun ammo is armor-piercing (effects incorporated into stats) and homing.