Yeah I guess not, just checked. Not sure how they get applied if they're completely separate from the model then.
It's the reason they cause such large fps drops. They are ran over what I can assume is an alpha map from the og weapons UV map, which means that they simply assign the texture to the special alpha channel, and it covers the gun in the camo. This requires more texture processing, but decreases overall memory usage because it stops there being 200 new models added for each skin on each gun.
It's a battle. Either better in game performance at the cost of a large download and larger game files, or small updates and performance dips.
An easy solution is the current system but the option to turn off skins, so those that rely on performance aren't held back by those that choose to run them.