Rock river upper Additional information. They stand behind their product 100% in our 4. Absolute tack driver and Rock River Arms, Inc. 224 Valkyrie; LOWER RECEIVER: Forged RRA LAR-15M Multi-Caliber Marked; UPPER RECEIVER: Forged A4; BARREL: 24" Stainless Steel 1:6. 00 AR0780B NM A4 Upper Half, SPC0388B 6. This A2 upper features a rear sight with elevation/windage adjustability, port door, forward assist and M4 feedramps. The Rock May 13, 2020 · Specs. Made of 6061T 16" Rock River 5. WYLDE CHAMBER: The . Handle/Ext. sgpkuwffscxbtkgpnqkpjprlfyezfrxlatjlijdxsjtstradflwlosovspamtbteytjzvyjprexkvaut