Simplify the following text for a Grade 10 native English-speaking person.
Original: The rest of the old Nitro express calibers were to fade almost to obscurity until a recent resurgence in safari hunting came about in the 1970s and 1980s .
Simplified: The rest of the old Nitro express calibers faded to obscurity until people starting safari hunting in the 1970s and 1980s .