Sons of Liberty Gun Works M4-EXO3 5.56 AR-15 Upper - 10.5"

3rd Generational Upgrades Include: EXO3 has a 4140 Steel barrel nut vs aluminum on EXO2 Updated proprietary lockup with a custom 4140 set screw that pulls the rail into the upper SOLGW added the anti-rotation pin from the M76/M89 Added slight finger grooves like the M76/M89 but not as pronounced Spaced out the lightening holes to stiffen the rail Specifications: Barrel: Sons of Liberty Gun Works 4150CoMOV 1:7 MPI HPT Barrel Caliber: 5.56 NATO Chamber Barrel Steel: 4150 CrMoV (Chrome Moly Vanadium per MIL-B-11595E) Twist Rate: 1/7 Twist Six Groove Thread Pitch: 1/2-28 Threaded Muzzle Gas Block: .750 Gas Block Journal with appropriately sized gas port Gas Length: Carbine Barrel Finish: QPQ Corrosion Resistant Finish Barrel Extension: QPQ coated M4 Feed Ramp Extension High Pressure (proof) Tested (HPT) Magnetic Particle Inspected (MPI) With "F" Marked Taper Pinned Front Sight Block Weight: 2 lbs 12.5 oz