Basically, its a plasma bolt that uses a reversed to-hit table. So, its most accurate out at range, while close-in its very INaccurate. Warhead is still half normal, so yeah, you can snipe, but the damage is crap. I see this as an ISC War thing, say, the Gorns developed it in Y186-7, with the Roms/Orions/etc copying it by Y188.

Note that an F-beam is going to suck rocks...mainly usefull for heavy plasma.