Mk 262
Parent case .223 Remington
Case type Rimless, bottleneck
Bullet diameter 5.70 mm (0.224 in)
Neck diameter 6.43 mm (0.253 in)
Shoulder diameter 9.00 mm (0.354 in)
Base diameter 9.58 mm (0.377 in)
Rim diameter 9.60 mm (0.378 in)
Rim thickness 1.14 mm (0.045 in)
Case length 44.70 mm (1.760 in)
Overall length 57.40 mm (2.260 in)
Rifling twist 1:7 (178 mm) rifling twist
Primer type Small rifle
Maximum pressure 430.00 MPa (62,366 psi)
Mass- 5.0 g
Velocity- 930 m/s (3,050 ft/s)
Energy- 2162 joules (1621 foot/pounds)
The Mk 262 is a match quality round manufactured by Black Hills Ammunition made originally for the Special Purpose Rifle (SPR). It uses a 77-grain (5.0 g) bullet that is more effective at longer ranges than the standard issue M855 round.
Two versions of the round have been procured to date. Initial production runs, designated Mark 262 Mod 0, lacked a cannelure. Subsequent production, designated Mk 262 Mod 1, added a cannelure to the bullet for effective crimping.
According to US DoD sources, the Mk 262 round is capable of making kills at 700 meters. Ballistics tests found that the round caused "consistent initial yaw in soft tissue" at 300+ meters. Apparently it is superior to the standard M855 round when fired from an M4 or M16 rifle. It evidently possesses superior stopping power, and can allow for engagements to be extended to up to 700 meters. It appears that this round can drastically improve the performance of any AR15 platform weapon chambered to .223/5.56mm. Superior accuracy, wounding capacity, stopping power and range power has made this the preferred round of many Special Forces operators, and highly desirable as a replacement for the older, Belgian made, 5.56x45mm M855 NATO round.[24]
