Mossberg 38179 817 Bolt

The
Ruger AR556, like its more expensive cousin the SR556, is packed with
features that fans of the Modern Sporting Rifle demand.
The
AR556 is direct impingement gas-operated with a 16-inch 1:8
hammer-forged barrel threaded 1/2×28. Also featured is a
windage-adjustable rear flip-up sight, a six-position telescoping
M4-style buttstock with a Mil-Spec buffer tube, M4 feed ramps, a
matte Type III hard coat oxide finish, enlarged trigger guard, a
chrome-plated bolt carrier, and an A2-style front post sight with
elevation adjustment, a bayonet lug and a Q/D attachment socket. This
rifle also comes with one 30-round Magpul PMAG.

Specifications:

Special Feature: Threaded Barrel Model
Weight: 6.5 lbs.
Rate-of-Twist: 1-in-8″
Sights: Adjustable Ruger Rapid Deploy
Additional Info: Flat Top M4 Design
Additional Info: Milled F-Height Gas Block
Additional Info: Improved Trigger Reach Grip