Machined, steel barrel bushings by ED BROWN are designed for a tight fit between the slide and barrel, specifically for the 1911 Government model with a blued finish.
The Drop-In version requires no fitting with Ed Brown Barrel and Colt slides, while other brands may need minor fitting; Oversize needs more adjustment for a match fit.
Product specs include a Drop-In (DI) with .581" I.D. and .699" O.D., and an Oversize (OS) with .575" I.D. and .705" O.D.; Commander version is available in Drop-In, Stainless Steel only.