question about BMG's

so i'm trying to get all the combat pursuits done for the outfits...have gotten through all of them with few problems but only have one left, getting level 10 in bmg's. i was wondering if someone could tell me if there is a specific bmg that is good for leveling or a certain way or place i should be using it or are the bmg's really that bad.

Stingray in a seige seems to do real good for level. I did mine on co op and ark falls mostly mine 99 co op. Try to critical damage more often it will go faster. But all in all it is a headache. Good Luck.