Buyers should always beware, and take steps to protect themselves.
1. Always ask for a no-fire inspection period, especially do this if you're paying more than you normally would for a used rifle. However, if you did the form 4473, it's now your rifle. I'd be hard pressed to take a firearm back if I have to do transfer paperwork, if I do it's coming out of your refund along with return shipping.
2. Seller offered to take more pictures, buyer didn't ask for any. It's in the original for sale post.
3. Two people, two opinions on condition. Q&A should have happened.
4. Now all this has been made public, there is no amicable ending. Neither party can be made whole at this point.