They all SUCK. I'm tryin to get the achievement for getting 10 kills with each B2K weapon. I've done the LMG's, the first was actually good, the MG sucks. Both PDW's are terrible, however I haven't used the PP19 post patch. The MK3A1 is. HORRIBLE. At a metre range you'd think that it'd be a one hit kill? NOPE, HITMARKER ***! Of course you have your good weapons such as the L85, L96 and the G36 (the FAMAS is terrible lol).