Yankee Hill Machine Co., Inc. Ar-15/M16 Gas Block
The Yankee Hill Machine Co., Inc. Ar-15/M16 Gas Block can be found at Brownells for $76.99, which is a pretty good price.
Five, fully functional, steel gas block designs provide much needed rail space or help you add long handguards to short-barreled rifles. Machined from bar stock for extra strength and rigidity, then mil-spec Parkerized for exceptional wear- and corrosion-resistance. One-piece, 4-Rail model features top/bottom and side rails that accept Weaver or Picatinny mounted, tactical accessories, including the Yankee Hill Gas Block Front Flip Sight. Secures to barrel with included setscrews. Low Profile version is a low and narrow, one-piece block designed to fit inside most free-float handguards; allows use of rifle length forearms on carbine length barrels for a clean, streamlined look and added gripping surface. Secures to barrel with included setscrews. 2-Rail gas block is an easy-to-install, two-piece unit that clamps around the barrel using four hex screws; includes machined top and bottom Picatinny rails only. Single-Rail gas block adds a top-side Picatinny rail for mounting accessories, and provides a bayonet lug and sling mount like a mil-spec front sight housing. Two-piece design clamps your rifle’s standard contour, .750″ diameter barrel with four, capscrews—no need to remove muzzle brake or flash suppressor to install. Bayonet lug accepts a mil-spec bayonet or lug-mounted bipod, and pivoting, rubber-coated sling swivel accepts tactical slings up to 1 ” wide. Specter model provides plenty of clearance to mount a free-float forearm that extends over the gas block, including Yankee Hill Specter handguards. Fits under any forearm with an inside diameter of 15⁄8″ or greater. Easy to install two-piece design eliminates the need to remove a pinned or welded-on flash hider or muzzle brake. Clamps securely to barrel with four, hardened steel, hex-head cap screws. SPECS: Steel, mil-spec phosphate finish. Fit standard, .750″ diameter barrels. 4-Rail – 17⁄8″ (4.8cm) long, 11⁄4″ (3.2cm) wide, 13⁄4″ (4.4cm) high. 5.7 oz. (162 g) wt. 2-Rail – 13⁄4″ long, 11⁄4″ wide, 13⁄4″ high. 5.4 oz. (153 g) wt. Single-Rail – 17⁄8″ (4.8cm) long, 13⁄16″ (3cm) wide, 1 ” (4.5cm) high. 5.5 oz. (155g) weight. Low Profile – 17⁄8″ long, 1″ (2.5cm) wide, 15⁄16″ (3.3cm) high. 4.4 oz. (125 g) wt. Specter – 17⁄8″ (4.7cm) long, 1 ” (3.8cm) wide. 4.4 oz. (125 g) weight. Fits barrel with .750″ O.D. at gas port.