So around 5 months ago, people found some new guns and attachments in the game. There was an attachable 7x scope for some guns, an underbarrel shotgun for the m16, and a m26 mass that was fully functional with animations and sounds. So what happened to those

If you read the free content roadmap post, it talks about what sort of new guns are coming as well as attachments. The mini shotgun and much more were mentioned.