Are there currently weapons you are not supposed to use? (PC)

I was playing a game on Operation Metro earlier today, I had just unlocked the F2000 the game before. I got a comment, a guy just said 'ofc Firepork' (my ingame tag is not Firepork, but I'm using it as a substitute). I only noticed it as I was leaving the server shortly after so I didn't get a chance to ask him what his comment was about.

I have not played BF4 in a few months so I was wondering if his comment was about be using a glitched weapon, is there a reason why I should not use the F2000 or any other weapons at this time?