Getting kills 'in genera' is easy with Infiltrator and personal shield - you can rinse and repeat with that - but doesn't help getting the mod attachments, sadly.
As for Blast - Mos Eisly, Moz's Castle, and Yavin IV have yielded good results for me plugging away for Specialist weapon mods. But I agree - some groups of guys are insane and then it's no good, no matter the map.
I never have any luck in GA - so I've been sticking to Strike - especially any carrier missions. Whether delivering or keeping back - it's easy to peg people in the head with any of the guns.
(edit: clarified first sentence)
