I'm not entirely sure if this is a common issue or if it's tied to the LOD bug that that is currently the problem of general performance. However, most of the time when I join a game since the latest patch/hotfix, I've noticed that it takes a full minute to 2 minutes or more for my guns to appear in first person, and then another minute for the attachments to appear. Sometimes this occurs with my player model as well. I don't know if this is a performance issue or a loading issue.
I will also point out that I have this game installed on an external harddrive rather than my main harddrive where I have steam installed, and that perhaps that could be part of the issue.