Skins not loading for launchers

I want to see it.........I get the new  shamrock lucky HE Launcher and equip it..... as an underslung and it remains as the standard issue. Would be nice if the skin changed even as underslung.....would be nice to see the work you put in get the achievement...shouldnt be only locked to standalone..,.if equipped regardless underlsung under a weapon we should be able to see the skin attached. i would like to see the skin attached underneath the weapon i choose if this is now an option