Some numbers:
Wep Damage Rng size Research Cost(medium)
APB XII 65..45 (8) 30Kt 1,600,000 (ROF 1)
Meson VI 35..35 (6) 20Kt 510,000 (ROF 1)
PPB V 60..60 (6) 30Kt 290,000 (ROF 1)
WMG III 140..140 (8) 70Kt 4,212,000 (ROF 3)
GHB V 145..40 (8) 60Kt 290,000 (ROF 2)
That Last one is the Graviton Hellbore V. Wow. I didn't realize that one was so easy to get compared to the Wave Motion Gun. Which would you rather put on your ship: a weapon that costs 1/14th as much to research and fires 50% more often and weights 10Kt less... Wow! (Granted, its damage definitely falls off over distance.)
Here are some other numbers:
Null Space Projector skips shields *and* armor and does this damage:
NSP III 60..60 (5) 50Kt 187,500 (ROF 3)
I might set the rate of fire on the Wave Motion Gun to 1 and let it fire every turn for a total research cost of 4.2 million and twice the size of the APB XII that costs a third as much to research.
With an ROF of 3, you could put 2 APB XII's on a ship and get 270 damage points at max range 8 every three turns compared to a single WMG doing only 140 damage points at the same range during the same timeframe. Plus... the WMG is more likely to miss and do no damage at all.
Anyways...
