The Pancor Jackhammer, I presume. If I didn't I couldn't well call myself a gun-nut. That thing is overly infamous among shotguns for both it's function and appearance.
Yeah, the design of it is rather fierce and. . . misleading. Still, it's pretty much an exotic piece. Matter of fact, US classes the thing as a machine gun because of how outrageous it is.
G11 was Germany's attempt to revolutionize small-arms by implementing caseless ammunition. That is, bullets that didn't need a shell to house the gunpowder. Had the idea work, it would've meant a lot less weight for our soldiers to carry today. But the designs for that thing are rather complicated and the functionality is less than desirable for most shooters.
I assume Beta-Century Drum magazine on that M4, it's the usual one people put on them. There's actually been a lot of developing into making a serviceable machine gun version of M4. Basically meaning they put in a heavier barrel, supply users with higher capacity magazines(US Marines are steering clear of drum mags) and so forth.
Personally, I think it was about time they get a magazine fed machine gun, the Russians have had them for almost half a century now. (Referring to the RPK series of Kalashnikovs)
Yeah those sound like the usual Kalashnikov victims of gaming. Don't have anywhere I can get Cold Zero from but from the sounds of it and my reading of it, the game's got quite a good weapon diversity for its time.