Ruger AR-556 5.56 NATO
Model: 8500
Ruger AR-556 5.56 NATO
Model: 8500
Full Specifications
About This Firearm
Ruger built the AR-556 around the same cold hammer-forged barrel process the company uses for its bolt-action precision rifles. The 16.1-inch 4140 chrome-moly barrel gets a matte black oxide finish, and the 7075-T6 receivers are Type III hard coat anodized. At 104 oz, the rifle sits right between the S&W M&P 15 Sport II (103.2 oz) and the Sport III (104.32 oz), and it ships with an A2-style front sight and Ruger's own Rapid Deploy folding rear sight.
The 1:8 twist rate matches the Sport III and handles 55gr to 77gr ammunition without issue. Ruger specs a 9310 alloy steel bolt, which is the same grade Springfield Armory uses in its SAINT line. The flat-top Picatinny upper receiver accepts standard optics mounts. One practical note from AR forums: the Ruger-branded flash suppressor uses a slightly different external profile than a standard A2, so some aftermarket muzzle devices may not index identically without a washer swap.
Best For
Strengths & Limitations
- Cold hammer-forged barrel, a process Ruger shares with its precision rifle lines, gives better bore consistency than the button-rifled barrels on the S&W Sport II and Anderson AM-15
- The 9310 alloy steel bolt matches what Springfield uses in the SAINT series, giving the AR-556 a stronger bolt than many rifles at this tier that use Carpenter 158 without heat-treat certification
- The Picatinny-only handguard cannot accept M-LOK accessories directly, putting it behind the Sport III, Anderson AM-15, and Del-Ton Sierra 316 for easy light and accessory mounting
- Ruger's proprietary Rapid Deploy rear sight is a polymer flip-up that some owners report feels loose after extended use, compared to the metal Magpul MBUS on the S&W Sport models
- At 2.5 inches wide and 8 inches tall, the profile is slightly larger than the S&W Sport II, though the difference is minor in practice
Category Rankings
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Alternatives to Consider
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Aero Precision M4E1 5.56 NATO
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Smith & Wesson M&P 15 Sport II 5.56 NATO
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Springfield Armory SAINT Victor 5.56 NATO
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FN 15 Guardian 5.56 NATO
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Frequently Asked Questions
How reliable is the Ruger AR-556 out of the box?
The AR-556 has one of the better track records in the budget AR segment. Owners on Reddit's r/ar15 and the Ruger Forum consistently report zero malfunctions through the first 500-1000 rounds with both brass and steel-case ammunition. The cold hammer-forged barrel and 9310 bolt contribute to long-term durability, and Ruger's warranty service is widely considered among the best in the industry.
Can the Picatinny handguard be swapped for M-LOK?
Yes, but it requires replacing the entire handguard and delta ring assembly, which runs roughly 30 minutes of work and a standard AR armorer's wrench. Many owners on the Ruger Forum recommend the Magpul MOE M-LOK handguard as a direct drop-in replacement. Alternatively, the AR-556 MPR model ships with an M-LOK handguard from the factory if you want to avoid the swap entirely.