The standard SMG uses a 10.5 inch barrel While using the regular “bird cage” flash suppressor and normal carbine handguards. The barrel provides a chrome lined bore and chamber. The barrel can also be produced in 16-inch size for the industrial/LE carbines. Posted by Phil Herbert on 22nd Apr 2023 https://colt105inch9mmsmgupperrec25786.blogripley.com/27274925/colt-smg-upper-receiver-for-dummies