Contact Colt, on line aucitons.
The Colt AR-15 is a sporter rifle
Contact Savage. They bought Steven in 1920.
Follow instructions in owner's manual
Follow instructions in the owner's manual.
Egunparts.
The owner's manual should have instructions. If not, list the make and model.
Contact Uberti Customer Service through their website and get an owner's manual. You did not say what MODEL rifle you have.
You contact Remington customer service, and ask for an owner's manual for your rifle. Then read and follow the manual.
See related links.
Its the length of the barrel. 24 for a sport and 28 for a target.
Follow the instructions in the owner's manual. If you don't have one, take it to a gunsmith and be shown.
A sporter air rifle and what?