Terminal ballistics M16 rifle

the original ammunition m16 55-grain m193 cartridge. when fired 20 barrel @ ranges of 100 meters, thin-jacketed lead-cored round traveled fast enough (above 2900 ft/s) force of striking human body cause round yaw (or tumble) , fragment dozen pieces of various sizes created wounds out of proportion caliber. these wounds devastating many considered m16 inhumane weapon. 5.56mm round s velocity decreases, number of fragments produces. 5.56mm round not fragment @ distances beyond 200 meters or @ velocities below 2500 ft/s, , lethality becomes largely dependent on shot placement.

with development of m16a2, new 62-grain m855 cartridge adopted in 1983. heavier bullet had more energy, , made steel core penetrate soviet body armor. however, caused less fragmentation on impact , reduced effects against targets without armor, both of lessened kinetic energy transfer , wounding ability. soldiers , marines coped through training, requirements shoot vital areas 3 times guarantee killing target.

however, there have been repeated , consistent reports of m855 s inability wound (i.e. fragment) when fired short barreled m4 carbine (even @ close ranges). m4 s 14.5 barrel length reduces muzzle velocity 2900 ft/s. reduced wounding ability 1 reason that, despite army s transition short-barrel m4 s, marine corps has decided continue using m16a4 20″ barrel 5.56×45mm m855 largely dependent upon high velocity in order wound effectively.

in 2003, u.s. army contended lack of lethality of 5.56×45mm more matter of perception fact. shot placement head , chest, target defeated without issue. majority of failures result of hitting target in non-vital areas such extremities. however, minority of failures occurred in spite of multiple hits chest. in 2006, study found 20% of soldiers using m4 carbine wanted more lethality or stopping power. in june 2010, united states army announced began shipping new 5.56mm, lead-free, m855a1 enhanced performance round active combat zones. upgrade designed maximize performance of 5.56×45mm round, extend range, improve accuracy, increase penetration , consistently fragment in soft-tissue when fired not standard length m16s, short-barreled m4 carbines. u.s. army has been impressed new m855a1 epr round re developing 7.62 nato variant.