Caliber: 5.56 NATO
Barrel Length: 20”
Barrel Profile: Pencil
Barrel Steel: 4150 Chrome Moly Vanadium
Barrel Finish: Parkerized
Chrome Lining: Yes
Muzzle Thread Pattern: 1/2" x 28
Twist Rate: 1/7
Barrel Extension: Rifle
Gas System Length: Rifle
Diameter at Gas Block: .625"
Gas Block Type: Rifle Height Front Sight Base
Muzzle Device: A1 style
Receiver Material: Forged 7075-T6
Upper Receiver Type: Slick Side M16A1 w/o feed ramps
Handguard Type: M16A1 Triangular, with heat shields
Bolt Material: Carpenter 158 Steel
Bolt Carrier Profile: Full Auto
Overall Length: 30 inches
Weight (as configured): 5 lbs

Features

These exclusive retro uppers are a throwback to the late 60's era 604s that features a grey anodized slick-sided upper receiver with a 20" parkerized 5.56 NATO barrel. The rifle length gas system and C158 BCG are paired to ensure smooth cycling and maximum durability. The later model 604 rifles also featured a mil-spec "birdcage" style A1 muzzle brake rather than the 3 prong brakes used on the previous versions. These complete uppers are hand fitted and assembled right here in the United States of America.

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Shipping Restrictions

It is the customer’s responsibility for understanding state laws regarding all purchases made. For a comprehensive list of all Shipping Restrictions, please refer to our Shipping Restrictions By State Page found Here.

All NFA Rules Apply

These items are controlled by the U.S. Government and authorized for export only to the country of ultimate destination for use by the ultimate consignee or end-user(s) herein identified. They may not be resold, transferred, or otherwise disposed of, to any other country or to any person other than the authorized ultimate consignee or end-user(s), either in their original form or after being incorporated into other items, without first obtaining approval from the U.S. government or as otherwise authorized by U.S. law and regulations.

Local Law Compliance

Certain firearm parts and accessories, including AR-style upper receivers, are subject to complex and frequently changing federal, state, and local laws and regulations. While an upper receiver may be lawfully sold and shipped as a component, the legality of possessing, assembling, configuring, or using an upper receiver in certain states (e.g., California, Washington State) and localities depends on how it is assembled, combined with other components, and ultimately used. You are solely responsible for ensuring that any assembly, configuration, possession, or use complies with all federal, state, and local laws, including any so-called “assault weapon” bans and short-barreled rifle restrictions. We do not provide legal advice and are not responsible for unlawful configurations or uses.

WARNING: Handling firearms or firearms parts can expose you to lead and other petroleum products known to the State of California to cause cancer, birth defects, or other reproductive harm. Wash hands thoroughly after handling. For more information go to www.p65warnings.ca.gov (CA Health and Safety Code Section 25249.6).