Chiappa Firearms M4 .22LR Upper 22 16in Upper Receiver Heavy Contour 1-16 Twist Quad Picatinny Parkerized Black. 22LR rifle perfect for plinking of training. The forend is a 7.8in long Quad Picatinny with a 16in steel barrel. Specifications for Chiappa Firearms M4-22 Gen II Pro .22 Long Rifle 16in Picatinny Upper Receiver w/7.8in Quad: Manufacturer: Chiappa Firearms Caliber: .22 Long Rifle Overall Length: 23.6 in Barrel Length: 16 in Barrel Profile: Heavy Contour Barrel Twist Rate: 1-16 Firearms Threads Per Inch: 1/2x28 Finish: Matte Color: Black Fabric/Material: Polymer Handguard Length: 7.8 in Gun Rail: Quad Picatinny Gun Type: Rifle Gun Make: Colt Gun Model: M4 Weight: 5.95 lb Barrel Material: Steel Magazine Included: Yes Package Contents: Chiappa Firearms M4-22 Gen II Pro .22 Long Rifle 16in Picatinny Upper Receiver w/7.8in Quad What firearm models does the manufacturer say Chiappa Firearms M4-22 Gen II Pro .22 Long Rifle 16in Picatinny Upper Receiver w/7.8in Quad is compatible with? The manufacturer says that Chiappa Firearms M4-22 Gen II Pro .22 Long Rifle 16in Picatinny Upper Receiver w/7.8in Quad is compatible with M4Chiappa Firearms 500093: M4 .22LR Upper 22 16in Upper Receiver Heavy Contour 1-16 Twist Parkerized Black