Question: are all remington 870 barrels interchangeable?
Answer: Remington® 870 Replacement Shotgun Barrels. Model 870 Barrels with 3" chambers will fit both magnum and 2-3/4" receivers and will handle both 2-3/4" and 3" shells with a magnum receiver. ... 870 Special Field barrels and other model 870 barrels are not interchangeable.