Ive been away for about 3 years, & ive recently just signed in to share something with you. I don't believe anybody has found this glitch, I am the founder.

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.
6. Voila.

When you start up your ps4, it will configure it self to a backup file, this back up file contains your weapon attachments.