Sons of Liberty Gun Works AR/M4 Stripped Broadsword Upper Receiver Sons of Liberty’s flagship stripped upper receiver, made from billet 7075-T6 for use with their M89 and L89 Drivelock rails. (Inside Diameter for barrel extension slightly undersized for a tighter fit to the barrel and a more accurate rifle. Please use a heat gun or hair dryer to warm up threaded bore of receiver if barrel extension is too tight.) Specifications Machined from billet 7075-T6 aluminum T marked Hardcoat anodized
