Let’s break down weapons systems…
A pistol can fire twice per round, deals 1D; range is in feet (half range); cost x1
A rifle can fire once per round, deals 2D; range is in feet; cost x2
A heavy rifle can fire once per round, deals 3D; range is in feet (double range); cost x5. A heavy rifle cannot normally be carried into combat, and requires two operators to move (although STR 14+ would allow a character to wield a heavy rifle in combat normally).
A light cannon fires once per round, deals 4D; range is x1; cost x20; base targeting +1
A medium cannon fires once per round, deals 5D; range is x2; cost x50; base targeting +1
A heavy cannon fires once per round, deals 6D; range is x3; cost x100; base targeting +1
Blast weapons deal D6 damage, base range 60/1, base cost 25 sc
Pulse weapons deal D8 damage, base range 120/2, base cost 50 sc
Phase weapons deal D10 damage, base range 180/3, base cost 100 sc
Weapon Breakdown (damage; range; cost)
1d6; 30’; 25 sc
1d8; 60’; 50 sc
1d10; 90’; 100 sc
2d6; 60’; 50 sc
2d8; 120’; 100 sc
2d10; 180’; 200 sc
3d6; 120’; 125 sc
3d8; 240’; 250 sc
3d10; 360’; 500 sc
4d6; 1 mile; 500 sc
4d8; 2 miles; 1,000 sc
4d10; 3 miles; 2,000 sc
5d6; 2 miles; 1,000 sc
5d8; 4 miles; 2,000 sc
5d10; 6 miles; 4,000 sc
6d6; 3 miles; 2,000 sc
6d8; 8 miles; 4,000 sc
6d10; 12 miles; 8,000 sc
For example, a planetary patrol vehicle is likely to have a heavy rifle position affixed to the top. A planetary tank or standard starship interceptor is likely to have a light cannon affixed. A medium freighter or similar vehicle may have a medium cannon, or a pair of light cannons. A heavy gunship may sport a pair of heavy cannons and eight medium cannons.
Blast weapons are the most common, and the most readily available. The make use of fundamental energy production technologies to focus a burst of accelerated particles at relatively short range. They were the first energy weapons created, and have found renewed popularity since the Messari returned. Many gno tinkers have made a name for themselves as developers of blast weapons, hand-crafting these in their personal workshops.
Pulse weapons emit focused lasers, giving better range and effectiveness compared to blast weapons, but with greater cost. Pulse weapons were the heart of the Confederate army before the Messari, but many have been destroyed, and their production facilities have been all but wiped out. It is difficult to craft pulse weapons without considerable production facilities.
Phase weapons are somewhat controversial, since they rely on subatomic fusion, and may in fact channel some form of anti-matter in their processing. These are exceptionally rare, powerful, and expensive weapons. It’s not likely that you’ll be able to purchase a heavy phase cannon to strap to the top of your modified transport. These also require precise engineering, and are difficult to manufacture without exceptional resources.
I like this breakdown, because it clearly sets everything out and provides a lot of variety.