To chime in again, I've used the forward assist, both for a time where I didn't let the bolt slam forward totally on it's own, and so the bolt did not go into battery. Slap the forward assist, and you're live. Similarly, if you check the chamber, you might need to hit the assist. Get one.
As for the dust cover, I have two cats. If I leave the dust cover open, the bolt gets covered in cat hair. Same with dust and such.
IMO, do the rifle right: chrome lined or melonited, chrome lined bolt, dust cover and forward assist.