Gemtech GVAC Upper Group Features The mil-spec upper receiver features indexing marks and M4 feed ramps machined from 7075-T6 aluminum and finished in Type III hard coat anodizing for durability. The 4150CMV steel barrel is stress relieved Armornite treated and 5R rifled with a 1:8 twist featuring the GVAC profile and a nickel boron coated barrel extension for smoother feeding and reliable bolt cycling. The muzzle is threaded 1/2x28 and capped with the Gemtech ETM flash hider a 4140CM steel muzzle device built to work in concert with the GVAC system. For shooters who want to significantly reduce suppressed gas blowback the GVAC s re-imagined barrel profile and muzzle device deliver that improvement directly. The mid-length GVAC gas system uses a pinned low-profile gas block made from 4140CM steel operating on direct impingement for reliable cycling. The enhanced bolt carrier group features a Carpenter 158 steel bolt and 8620 steel carrier mil-spec MP tested with a Mag-Phos finish chrome lining a properly staked gas key and a chrome firing pin for long-term reliability. The 10.5 inch Midwest Industries Combat M-LOK free-float handguard is seven-sided with a continuous MIL-STD 1913 Picatinny top rail and integrated QD sling sockets machined from 6061-T6 aluminum and Type III hard coat anodized. For builders who want a complete suppressor-optimized upper with premium components throughout the Gemtech GVAC Upper Group delivers that in a single drop-in unit. Gemtech GVAC Upper Group Specifications Manufacturer: Gemtech Model: GVAC Type: Accessory Upper Upper Receiver Caliber: 5.56 NATO / .223 Rem Barrel Length: 11.5 in Barrel Material: 4150CMV Steel Barrel Description: Stress Relieved 5R Rifled GVAC Profile Nickel Boron Coated Extension Twist Rate: 1:8 Finish: Armornite Thread Pattern: 1/2x28 Special Feature: Threaded Barrel Upper Receiver Material: 7075-T6 Aluminum Type III Hard Coat Anodized Gas System: Mid-Length GVAC Direct Impingement Gas Block: Pinned Low-Profile 4140CM Steel Muzzle Device: Gemtech ETM Flash Hider 4140CM Steel Bolt Carrier Group: Carpenter 158 Steel Bolt 8620 Steel Carrier Chrome Lined Mag-Phos Finish Handguard: 10.5 in Midwest Industries Combat M-LOK 6061-T6 Aluminum Compatible Hosts: M&P15 Most AR-Style Lowers Weight: 57.6 oz Available At: GrabAGun