Beside the 5 second light-speed limit, another reason for restricting beam range is that beam weapons have unlimited ammunition and have no counter. Currently, if you out-range your opponents in beam combat it is generally not by a huge amount and they don't have to be much faster to close the range in a reasonable time. If beam weapons had significantly longer ranges then one side could be at huge disadvantage. If you outrange an opponent with missiles, he can still shoot them down and you have to build and transport those missiles.
I wouldn't say that beam weapons (with the exception of mesons) have no counter. Shields at the same tech level will stop beam fire cold at all but the shortest ranges as long as fuel is available. At least the way I use them in ship design they will.
Common practice for most players is to design warships that use 5+ layers of armor and no shields, I tend to use about half that amount of armor and fill the "unused" armor hs's with shields*. even at ranges where BFC's are at 50% hit rates the actual damage is usually 25% or less of the max potential. The combination low hit probability and low damage means that the shields can recycle faster hull space for hull space than the damage can accumulate. This of course is only in a ship v ship scenario.
*-In actual practice I use a % formula based on projected ship size to determine armor and shield needs.
Using the example 25cm-UV-C4 laser/31cm-UV-C4 spinal laser/38cm-UV-C4 advanced spinal laser. The rof's are 20/35/50, and hull space usage is 8/10/12. Epsilon shields(3pts)/regen 3/BFC 50%-40k km are the matching tech. The 4X range BFC is 50% at 160k/km. Damage at this range for the lasers are 4/6/9 respectively. The shields can easily handle this at equal hs usage.
Even if the highest level BFC was changed to an absurd level to allow a max laser a 1% chance to hit at max range(80cm Gamma Ray/20.1mkm) the damage potential at a 'mere' 1.4mkm(hit chance 93%) is only 14 (down from the max a 168) and a singe max Omega shield is rated at 15. With the laser being 25hs in size the same space in shield can withstand 375pts of damage, with the matching regeneration tech they will fully recycle in 5 minutes. In the same time the laser will only get 8 shots (rof 35) which means the shields will counter the laser shot for shot, hull space for hull space as long as the fuel holds out and the range stays open.
Not saying that the beam ranges should be changed though. Just an examples that it would not be as unbalancing against the existing tech as is commonly presumed. The profile of degrading beam damage over range negates most of the potential of beams ability to inflict damage beyond very short ranges, especially if existing tech shields are being used.
Too offset the unlimited nature of most beams have powerplanets require fuel usage to produce a power point at the same rate as engines produce a propulsion point.
I could make the range increments cheaper so you have a slightly longer range earlier, but I want to avoid huge beam weapon ranges.
As things stand, I'd recommend leaving the current range increments stand. With the caveat that users with database access can still make personal changes to allow greater BFC ranges. This of course is with the usual stipulations about bug reporting related to user database changes (ie don't).
An alternative would be to code a hit bonus if the BFC has a greater tracking speed that the target. I haven't looked into what kind of imbalancing properties this may introduce, it's merely an off-the-cuff idea.
Another option I am considering however is to remove the atmospheric restrictions on beam weapons and give planetary-based beam weapons a similar type of enhancement to spinal weapons. Longer range is less of an issue when you can't move. Beam-armed PDCs on the same planet wouldn't be able to fire at once another (except for mesons). If I did this though, that raises the issue of using beams to cleanly wipe out planetary populations (which is why the restriction was added in the first place). To avoid that I can see two options:
1) Make ground-based installations and populations immune to beam weapon fire - each one is spread over a large area and beam weapons are precision weapons. Allow beam weapons to act as fire support for ground combat - adding to combat strength up to perhaps an amount equal to the ground combat attack strength.
2) Allow beam weapons a chance to fail with each shot. Not as keen on this as it removes one of the main advantages over missiles.
Steve
Dropping atmospheric restrictions sounds interesting. It does open up some possibilities. My suggestion is to only have populations immune from direct loss from beam weapons. But make installations (factories/mines/etc) susceptible to direct beam fire. Said beam fire does ramp up atmospheric dust and possibly background count. Maybe they need to inflict more damage than missiles to destroy installations representing the spread out nature of the targets vs precision beams.
If a failure possibility is added to beams per shot then missiles really should get one as well. Base failure rate could be based on the existing systems failure rate and be incremented is some fashion after x-number of firing cycles. The additional failure rate could be decrement based y-number of non-firing cycles (non-firing cycles could be days/weeks/months/etc). This would actually take a step towards representing combat usage impacting reliability and proper maintenance offsetting combat wear.