Overview:
Building off the success of our highly-accurate and reliable OBR 7.62, we set out to apply the same proven design features into a 5.56 rifle. The result is a lightweight, and reliable, tack driver that remains cool…even after high-rates of fire. The barrel and barrel nut does not touch the handguard at any point, so there is very little heat-transfer to your support hand. Like its 7.62mm sibling, both the upper and lower are CNC-machined from billet 7075-T6, for the optimum fit and consistency...translating into maximum accuracy. Even though this is a complete rifle, the upper will fit to any Mil-Spec AR15/M16 type lower.

The continuous upper-rail provides plenty of room for weapon-mounted night-vision day/night combinations and provides correct ballistic orientation for all inline night-vision combinations. The 10 MOA cant gives users an added advantage when using magnified optics at longer distances. A step-down at the rear of the receiver creates zero MOA for use of BUIS’s at shorter distances.

Each rifle ships with three, 3” long, MIL-STD-1913 detachable rail sections  that they can be configured anywhere along the entire length of the handguard (via threaded steel inserts), for the interface of MIL-STD-1913 equipped lights, lasers, bipods, grips, tripod mounts, etc.

Barrels:
The barrels are LW-50 stainless steel in 12”, 16.1", 18" & 20" lengths. They are Wylde chambered, and feature polygonal rifling in a 1/8 twist rate. We have used these barrels with great success for years in our popular and accurate Stealth uppers. LW-50 Stainless has proven itself for over 15 years, in military and civilian uses ranging from sniper, tactical, target, and other high-performance applications where long life and accuracy are critical.

All barrels are threaded in ½ x 28, with an A2 flash hider attached (other muzzle devices can be added at an additional cost).
The 12” model have carbine-length gas systems, the 16” and 18” models has a mid-length, and the 20” has a rifle-length. All gas blocks will feature our unique Port Selector Technology (PST), a two-point adjustable gas selector that allows optimum function between suppressed, and unsuppressed operation at the flip of a switch.

Internals:
The Bolts and Bolt Carriers are hand-polished hard-chrome with max-staked carrier keys. The carrier key contact areas are surface-ground flat for zero gas leakage. The trigger group is the same excellent Geissele SSA Combat Triggers we use in the OBR 7.62.The SSA provides an average 4.5lb pull weight.(2.5 lbs on the first stage and 2lb on the second stage).

Furniture:
The 12”, 16”, and 18” models come with a 6-position Magpul CTR and MOE Pistol Grip in LaRue UDE. The 20” Model Comes with an A2 Grip and A2 Stock, in black.

Features:
- Guaranteed sub-MOA accuracy (with Federal GMM, 77 grain ammo)
- Proprietary handguard design keeps the rifle cool, aids in accuracy and ease of handling
- Unique fully freefloating barrel and barrel-nut design, that does not touch the handguard at any point, aids in accuracy
- Upper, lower and rails are CNC-machined from 7075-T6, Type-III hard anodized
- 10 MOA built into a continuous, T-marked, 1-piece upper rail
- Drop-down at rear of rail, for zero MOA when using iron sights
- Lower is low-shelf, to accommodate RDIAS
- Flared magwell allows faster mag changes
- Large trigger opening, with integral trigger guard
- Bolts and bolt carriers are hand-polished hard-chrome, in M16 profile
- LW-50 stainless steel barrels in 12”, 16.1", 18" & 20" lengths
- Barrels are finished in black Manganese Phosphate
- Wylde chambered in 5.56mm NATO
- Polygonal rifling
- 1/8 twist-rate rifling.
- 10,000-round barrel life (approx)
- Muzzle threading: ½ x 28
- Direct gas-impingement: 12” is carbine-length, 16” and 18” are mid-length, and 20” is rifle-length
- Port Selector Technology (PST) gas block
- Geissele SSA Combat Triggers, two-stage, average 4.5lb pull weight.(2.5 lbs on the first stage and 2lb on the second stage)
- Mil-Spec receiver extensions on 12”, 16” and 18”
- Three, 3” long, MIL-STD-1913 detachable rail sections (and mounting hardware) included
- Magpul CTR Stock, UDE colored, on 12”, 16”, and 18” models (The 20” comes with an A2 Stock, in black).
- Magpul MOE Pistol Grip, UDE colored, on 12”, 16”, and 18” models The (The 20” comes with an A2 Grip, in black).
- Weight of 16” model (with 30 round magazine): 8.79 lbs

Models Available: 
(Iron Sights, Optics and QD mounts not included in price)

OBR 556, 12” SBR
(LT556-12)  With UDE Magpul CTR Stock and MOE Pistol Grip, 2 Pmags, 3 Rail Strips, and A2 Flash Hider
(This is an SBR, All NFA rules apply)

OBR 556, 16”
(LT556-16) 
With UDE Magpul CTR Stock and MOE Pistol Grip, 2 Pmags, 3 Rail Strips, and A2 Flash Hider

OBR 556, 18”
(LT556-18)  With UDE Magpul CTR Stock and MOE Pistol Grip, 2 Pmags, 3 Rail Strips, and A2 Flash Hider

OBR 556, 20”
(LT556-20)  
With Black A2 Stock and A2 Pistol Grip, 2 Pmags, 3 Rail Strips, and A2 Flash Hider