These were ideas that Steve came up with (I think that they appear in SA), from memory, they work much like the regular AMBAM. Functionally the BAM-Rc & BAM-G versions were identical, cost was I think 1.5 MCr for the BAM-R, 5 Mcr for -Rc/G, range was 2 tacHex for -R, 5 TacHex for -Rc/G (no ability to attack point sources such as individual ships tho), and the -Rc/G could take out 2 patterns of mines, the -R only one. The other big difference that I recall was that the Rc/G version was actually bigger than the base missile (2.5 MSP rather than 2).
This was about the same time as he came up with the Mine Racks and other items to try and counter the InstaMegaMineField (tm), and not long before the 1st Great Schism.