The Airmaster77 is made by Crosman. It's the same as the Crosman 2100, but with a different finish and the Remington name slapped on it. You can request a new catalog here:
http://www.airguns.com/contact (under "Message for", choose 'Request owners manual'. They also require the serial number.)
Or you can download it here:
http://crosman.com/site/rifles_man (click on the number in the Owners Manual column.)