Your PS4 System contains a backup file stored with game data & other stuff.
1. Reach Level 55
2. Go to Prestige Mode
3. Hover over Enter Prestige
4. At the same time, Press X to enter Prestige & immediately pull the power cord out from your console.
5. Plug the power back in, Start MWR.
When you start up your ps4, it will configure it self to a backup file, this back up file contains your weapon attachments.