Background

Built in house by SEAL Team armorers, and later by the Naval Surface Warfare Center, Crane Division (often referred to as NSWC-Crane or just Crane), these rifles were developed to provide SEAL snipers with a portable, lightweight system that had greater lethality over a standard M4-type AR-15/M16 pattern carbine. When greater production of these weapons was turned over to the personnel at Crane, there is some confusion as to exactly what happened, but Army money and ideas (from the Special Purpose Receiver project) got funnelled into the process. The SEAL teams were apparently disappointed with the performance of the resulting Mk 12 Special Purpose Rifle (SPR), and have apparently now convinced the managers at Crane to return to center as it were. Production of 'Recon Rifles' on the original pattern is progressing now according to some sources.

Specifications

These weapons were intially built in house with the only real specifications being the ability to shoot any 5.56 x 45 mm cartridge in inventory (at the time this did include the first iterations of the 77 Grain Mk 262 5.56 x 45 mm cartridge), and that the weapon have a 16 in (406 mm) long barrel.

The barrel blanks are made by Lilja Precision and then chambered by Compass Lake. They have a 1:8 in (203 mm) twist and are stainless steel. They have a unique heavy barrel profile, starting with 0.980 in (25 mm) in diameter for the first 2.60 in (66 mm) of length, then narrowing down to 0.850 (22 mm) in diameter, 0.750 in (19 mm) in diameter underneath the front sight block, and 0.725 in (18 mm) in diameter to the muzzle. The barrels have the Knight's Armament Company - KAC QD (Quick Detach) flash hider, allowing the mounting of KAC's QD sound suppresor. A carbine-length gas system is used. These barrels were mated to flat top upper receivers, and retained the fixed front sight/gas block assembly, which would seem imply the original iterations were probably just rebarreled M4/A1 type carbines in SEAL inventory.

Beyond this, exact specifications vary. Since they were built in house, they seem to have been accessorized to personal preferences, with fixed or retractable butt-stocks, various BackUp Iron Sights - BUIS (with the KAC 600 meter unit being the most popular), and a variety of optics. There is no mention of the use of a rail handgaurd of any kind, but there is little doubt one could be fitted.

Whether or not these specifications have changed with regards to Crane's 'production' weapons is unknown.

See also

• United States Navy Mark 12 Mod 0 Special Purpose Rifle
• Knight's Armament Company