The demand for a small but effective Light Assault Weapon is eminent. The trend has been to shorten already existing weapons like US M16 or Russian AK-74. The results you can see on the pictures below - M4 and AK-74U. This is a double-edged matter. The gun will be shorter, BUT the short barrel will have negative consequences on the bullet’s velocity and its performance. This is a known fact since WWI. Less velocity will result in reduced penetration in hard targets and reduced effect in the soft targets. With other words – bullets fired from these types of weapons will fail to penetrate body armour or be less lethal. For example David Crane at Defence review says: "It's no secret that the performance of both the M4 Carbine and it’s 5.56x45mm caliber have, so far, been somewhat less than outstanding in the war against Al-Queda forces in Afghanistan. In short, the enemy hasn't been dropping quickly enough when they are hit. Apparently, the M855 has been zipping right through the bad guys, leaving clean holes out the other side." The reason for this is the retarded bullet velocity of the 5.56 M855 cartridges when shot from the short barrelled M4 Carbine.