GhostRecon
Mongoose
The suggestion I made was a combination or exclusive use of A) Halved AD for the beam weapon and B) Raising the 4+ for a beam hit to 5+
The only "iffy" application of the rule is to 1 AD beam weapons, in which case I suppose the best fit is using the 5+ to hit rule, or even raising it to 6+, alternatively, in all cases, the beam hit can "ramp up." For example, the first hit rolls 4+, then 5+, then 6+ like interceptors, reflecting the fact the beam shot is "raking" across the target instead of burning through it, and thus is less effective.
One could even just use the "ramp up" to reflect raking fire; you keep your normal amount of AD, but the "to hit" needed ramps up to 6+ until you're out of AD Dice.
The only "iffy" application of the rule is to 1 AD beam weapons, in which case I suppose the best fit is using the 5+ to hit rule, or even raising it to 6+, alternatively, in all cases, the beam hit can "ramp up." For example, the first hit rolls 4+, then 5+, then 6+ like interceptors, reflecting the fact the beam shot is "raking" across the target instead of burning through it, and thus is less effective.
One could even just use the "ramp up" to reflect raking fire; you keep your normal amount of AD, but the "to hit" needed ramps up to 6+ until you're out of AD Dice.