Sig Sauer is known for its reliable piston-driven rifles. When it also dove into the direct-impingement AR world with the M400, it brought along its reputation for quality. In the upcoming November 2014 issue of GUNS & WEAPONS FOR LAW ENFORCEMENT, author D.K. Pridgen test-fires the new M400 SRP (Sight-Ready Patrol) in 5.56mm NATO.

Pridgen writes, “It was obvious from the get-go that Sig Sauer hit a homerun with the M400 series. Every M400 rifle in the series features a top Picatinny rail; upper and lower receivers forged from 7075-T6 aircraft- grade aluminum and hardcoat anodized; a cold-hammer-forged, chrome-lined, phosphate-coated, 16-inch barrel (the Hunter variant’s is 20 inches) with six-groove, 1-in-7-inch-twist rifling; a 5.56mm NATO chamber; a six-position commercial buffer tube/receiver extension with a firmly staked castle nut; a mil-spec trigger; the direct impingement operating system; an A2-style birdcage flash suppressor (the Hunter has none); M4 feed ramps; a phosphated commercial bolt and carrier with a properly staked gas key; a reasonably flared magazine well; and integral quick-detach (QD) sling attachment points on both sides at the rear of the lower receiver.

“All M400s, except for the Hunter and the Sight Ready Patrol (SRP), arrive with sights in place—a folding rear unit and an elevation-adjustable, ‘F’-marked front sight tower. The SRP has no sights but uses a low-profile, railed gas block to allow for attaching a front sight, while the Hunter has no provision for attaching a front sight. On the Enhanced series, Magpul furniture (stock, pistol grip and forend) is used. The Hunter uses an A2- style fixed stock with a Magpul pistol grip and forend. The Classic, SRP and SWAT use standard A2 six-position collapsible stocks and pistol grips. The Classic and SRP have traditional forends with double aluminum heat shields, while the SWAT features a two-piece railed forend.”

To learn more, check out the November 2014 issue of GUNS & WEAPONS FOR LAW ENFORCEMENT, available on newsstands and digitally Sept. 16, 2014. To subscribe, go to

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