 Under federal regulations, these changes make the Model 1927A1 legally a rifle and remove it from the federal registry requirements of the National Firearms Act.These modern versions should not be confused with the original semi-automatic M1927, which was a slightly modified M1921 produced by Colt for Auto-Ordnance.The Model 1927A1 is the semi-automatic replica of the Thompson Models of 1921 and 1927.