Call of Duty: Black Ops III

The achievement doesn't seem to be glitched anymore as I just began playing the campaign and had to obtain it legit.

The quickest way to do it would be to go into combat immersion which is accessed from the safehouse and use a secondary on recruit, the secondaries only require 150 kills to unlock all the camos. You could get it easily within 30 probably less minutes that way, alternatively if you plan on beating the campaign if you stick to one gun you should just get it as you progress.

**** This achievement is glitched. It will unlock with a small amount of kills with one weapon.

You need to get 650 kills with the same weapon to unlock all the camos for said weapon.

If this one doesn't glitch for you, as it did not for me:

In the mission Hypocenter, at the point where you have to disconnect the server system, there are 3 grenades that need to be placed into it. Go ahead and do the first two. At this point there is an infinite respawner for exploding robots. Just run backwards in a circle around the edge of the server system and just kill them all, they drop very easily. They also seem to drop ammo (I was using the Kuda) and there is also an ammo box here. I went into the level with 275 kills on the Kuda and it stormed up to 650 in no time.

Hope this helps someone who was also as unlucky as me not to get the glitch!