I have a few already
I have the MP7, PDW, Skorpion EVO, (going for diamond SMG) The R870 MCS, DSR 50, FHJ18-AA (lock-on launcher) and I have diamond specials (gold Combat Knife, Crossbow, Ballistic Knife and Assault Shield) I may have more but I'm not on the game to be able to check. I am close to getting 3 other guns gold right now. (I dont go for one gun at a time, too boring and no variety)
Edit: I don't play this game too much, but since I posted this I now have Diamond Specials, Launchers, SMG's, and Snipers. I also have a gold M8A1 and R870 MCS. I'm proud of them
got a lot to go though... LMG, Assault Rifle, Shotgun, Pistols. 20 gold, 21 or so to go! ...at least since I'm very close to Prestige Master with almost 6 days played, I can have something to do still! Probably take me around 10 more days played since the pistols will be hard and I don't like assault rifles.