Found a very nice word document that goes into great depth about the different weapons systems used in game. Everyone should get this, in fact I recommend GoG make it part of the game extras on the games download page, though I don’t think this is an official document from the developer.

Looks like the issue with the Photon Torpedoes not hitting much is probably due to players not using them properly. Beyond range 8 only fire proximity shots, it then has some really nice hit chances as long as you are winning the ECM shift (range 9-13 67%, 13-30 50%).

http://www.dynaverse.net/downloads.php?id=7&game=SFC 1#download

Here’s a cut and paste of a couple paragraphs covering the Photon Torpedoes:

The critical ranges for the photon torpedo are 0-1, where it can't miss assuming no ECM shift, but causes feedback damage. 2, where it is very accurate and does not cause feedback damage. 4, where it is reasonably accurate (67%) and outmatches most other weapons. 8, the outer edge of overloaded weapon range (50%). 13, the furthest distance for firing proximity warheads with a 67% chance of hitting, and 30 (50% proximity, where massed firings from a fleet can do serious damage while outside the effective range of most other weapons).
The photon torpedo is unique among direct-fire weapons in that the damage it causes does not degrade with range. At all ranges, 0-8, an overloaded photon does 16 points of damage. A normal photon does 8 points of damage from range 0 to 30, and a proximity photon does 4 points from 9 to 30. It is the only direct-fire weapon with this property.


Edit: Hmmm... The link won't take you to the download if you click on it. But if you copy paste it into your address bar you'll go right to the download.