Metro Last Light

If you would rather not waste any bullets working toward this you can wait until the last level when you are defending D6. There will be a weapon wall and gives you the ability to customize the weapons for free. I did it with the saiga, it should pop when you exit from the wall.

Phoenix0689 is spot on.....but misses something fundamental HOW TO GET THE ACHIEVEMENT

His guide states that the weapon wall is free for customizing which is correct and thats whats made it the top solution. The actual way to get the achievement earlier on is to ensure the weapon you own has all the customization attachment options on it!

I used my pneumatic weapon called Tihar (Tikhar) and the attachments is has to be added are

OPTICS
- 2x zoom sight called '2 Sight'
- COD style 'reflex sight'
- Nightvision 'IR sight' (Infrared)

Miscellaneous
- 'Lazer Sight' Improves accuracy
- 'Airtight Valve' Stops weapon leaking air when over pressured

NOTE You are able to have both misc attachments on at the same time so please do that

Alls you need to do is buy all the attachments (YES that means you have to uninstall one to replace it with the other). Do the same for both the Optics and Misc and then come away from the wall and the achievement should POP

I wrote this guide because i had 1000 militray round and when I attempted it legit, it didnt unlock.