The Chiappa MFour Gen II Rimfire AR-15 Upper Receiver Assembly is ready to convert any standard AR-15 into a rimfire carbine for reduced cost practice, training, or introducing new shooters to the most popular rifle in America. The Chiappa MFour Gen II is a dedicated rimfire upper receiver features an 16″ barrel with a Flat-Top upper receiver and free float handguard. The free float handguard provides a continuous top rail and full length Picatinny rails at the 3, 6, and 9 o’clock positions. This enables users to mount any accessories they use on their centerfire upper which helps when using the MFour Gen II Upper for training purposes.

The Chiappa MFour Gen II Rimfire AR-15 Upper Receiver Assembly features a parkerized steel, heavy profile, match barrel. The receiver itself is made from a reinforced, improved polymer that is very similar to aluminum. The polymer receiver provides a strong but extremely lightweight housing for the steel bolt.

The Chiappa MFour Gen II Rimfire AR-15 Upper is economical, reliable, and an excellent choice for introducing young shooters and keeping skills sharp at a lower cost than training with .223/5.56 ammunition. This upper fits any Mil-Spec lower receiver and requires no permanent modification to the host firearm.