[SGII] Fire of AT Missiles at disperesed tagets

Hi,

Just a quick question from Sunday's game. My opponent had a very small
but 
heavily armed SF section that wished to fire his GMS/P at an infantry 
section in hard cover. I allowed it, giving the thing FP D10 and Impact
D8 
(the same as a heavy weapon fired at a dispersed target). What do you
think?

Richard