O.K. Good to hear that he didn't fire the gun with another bolt.

It sounds like it has already been sent back to Remington but if not....... Take a non fired cartridge and tape a piece of masking tape on the case head. Trim with a razor blade so that it does not stick out past the side of the case and try to close the bolt. If it closes easily the head space is likely excessive. If it is hard to close the bolt then it most likely isn't head space but more likely a rough chamber or possibly ammo loaded too hot.