I'm having quite a lot of success using the Medium Shotgun, so I figured I'd try going a Heavy Body and using the Heavy version. However, I can't seem to kill anybody with it; seems that eventhough I ram it down their throat (or up their...backside) the pellets don't seem to hit them.

Is the range supposed to be this much shorter than the Medium Shotgun?

looking at the weapon stats here: http://denkirson.xanga.com/738334226/brink/
which should be right is the heavy shotgun more accurate but deals less damage.

It's really hard to use due to high accuracy and recoil at the same time.

It's the opposite for me, I can easily net kills with the hjammerdeim, but the mossington fires to slowly to be of any use in a close quarters fight. According to denkirson, the mossington does 220 damage per shot, while the hjammerdeim does 128. Those may be the hard numbers, but that means that the mossington at point blank should 1-shot any medium or light regardless of their buffs, and should easily 2 shot any heavy regardless of buffs. I've not found that to be the case, as the mossington usually takes 3-4 shots on mediums/lights and several more for heavies. There is no headshot bonus for either shotgun - they do the same damage regardless of where you hit the target (assuming you hit with all 10/8 pellets).

The only time I can ever really get kills with the mossington is if I sneak up on someone and get in at least one shot before they can react, and even then if the target has an smg and turns around quick enough I'm toast no matter what I do. The Hjammerdeim seems to only require 2 shots for mediums, 3 for mediums that have buffs, it hits more reliably and it can fire 2 shots in sequence before having to spin the drum.

I just wish I could use the hjammerdeim on my medium body type... really dont like playing heavy =/