EAW and OP do not use the same scheme as Community Edition uses for determining Plasma's range. EAW/OP Torpedoes will match their chart-based damage with a mere +0.05 extension. A Phaser-1, on the other hand, has an extension of +0.99, such that it does the same damage at range 5.00 through 5.99. We are all very accustomed to that convention.
But EAW/OP Plasma doesn't work this way. If your G-CA fires at a nominal range of 10 (let's say 10.92) from an immobile target, you will not do 20 damage per Plasma-G. You'll do 15 instead, as if you were firing at a nominal range of 11.
In Community Edition, I believe the coders might have tried to give Plasma the same +0.99 extension that all direct-fire weapons have. It makes sense to me... But I've discovered that this new extension is too big (or perhaps the rate of decay is slightly low).
The Plasma-G can do 20 damage at a range of 11.5. It's over-reaching by 0.5.
At range 21.7, it can do 1 point of damage. It's over-reaching by about 0.8.
The Plasma-R, however, gets a bigger extension due to its great endurance, over-reaching by up to 3.4. The Plasma-R should not do 10 damage after travelling 32.6 hexes! It should stop doing 10 damage at range 28.9. And be completely exhausted at 30.9.
There's a slight error that's being compounded. It's trivial for Plasma-D/F, but substantial for larger torpedoes.
(The attached image shows the movement of plasma that is properly not counted against it in CE because the models are 6000 miles long. Range in SFC is determined shield to shield, not center to center. This peculiarity may influence the Plasma "charts", wherever they may be.)