For cluster weapons, if you want to concentrate damage a lot more, you could go with DFA's hit location method.
1d6 pilot die, 1d6 per cluster that hit, combine the results.
Example, LB10 hits with 7 clusters:
Pilot die result: 3
Cluster results, 3,4,3,2,5,4,4
Hits: RT,CT,RT,RL,LT,CT,CT
Results should spread around a central location. The only thing that gets weird are head hits and TAC's since their on the far sides of the bell curve.