Mk318 effective against personnel with or without body armor. The round also increases accuracy, from 3–5 minute of angle (MOA) with the M855 from an M4A1 barrel to 1.71 MOA at 300 yards and 1.67 MOA at 600 yards from a SCAR-L barrel. For general issue, the U.S. Army adopted the M855A1 round in 2010 to replace the M855. The primary reason was pressure to use non-lead bullets. The lead slug is replaced by a copper alloy slug in a reverse-drawn jacket, with a hardened steel penetrator extending beyond the jacket, reducing lead contamination to the environment. The M855A1 offers several improvements other than being lead-free. It is slightly more accurate, has better consistency of effect in regards to wounding ability, and has an increased penetrating capability. The 62 grain (4.0 g) projectile can better penetrate steel, brick, concrete, and masonry walls, as well as body armor and sheet metal. It penetrates of mild steel at 350 meters, which the M855 can only do at 160 meters. The propellant burns faster, which decreases the muzzle flash and gives a higher muzzle velocity, an important feature when fired from a short barreled M4 carbine. Though the M855A1 is more expensive to produce, its performance is considered to compensate. One possible danger is that it generates much greater pressure in the chamber when fired, decreasing service life of parts and increasing the risk of catastrophic failure of the weapon (though this has yet to occur). The U.S. Marines adopted the Mk318 in early 2010 due to delays with the M855A1. This was a temporary measure until the M855A1 was available for them, which occurred in mid-2010 when the Army began to receive the rounds. Both the Mk318 and M855A1 weigh the same and have similar performance, and both have better performance than the M855 against all targets. SOCOM spent less money developing the Mk318 and it is marginally better than the M855A1 in some situations, but costs more per round. The Army spent more developing the M855A1 which performs as well or nearly as well as the Mk318, but is cheaper per round and has the advantage of being lead-free. While SOCOM constantly looks for better equipment, the Army and Marines have far more troops to supply and buy more ammunition than SOCOM. Alternatives If the 5.56 mm bullet is moving too slowly to reliably yaw, expand, or fragment on impact, the