<P> In 1984 , the first model was made , and it was tested in May 1985 . The first model have a Upper A1 Sight , and was given a shorter 11.5 - barrel , but later it was giving a longer 14.5 - inch barrel for the bayonet and the M203 Grenade Launcher . The second model was made in May 1986 , and it was tested from May 1986 though May 1987 , at the time it have a A2 Upper Sight , and it have the M16A2 's 1 : 7 inch rifle twist , to use the heavier 62 - grain M855 rounds . The extended barrel improved the XM4 's ballistics , reduced muzzle blast and gave the XM4 the ability to mount a bayonet and the M203 grenade launcher . The XM4 was also given the cartridge deflector , as well as other minor refinements . In May 1991 , the XM4 was renamed to the M4 , and Colt made a manual . In 1994 , the U.S. military officially accepted the M4 into service to replace M16A2s in certain roles . The M4 carbine has also replaced most submachine guns and selected handguns in U.S. military service , as it fires more effective rifle ammunition that offers superior stopping power and is better able to penetrate modern body armor . </P>
<P> In 1984 , the first model was made , and it was tested in May 1985 . The first model have a Upper A1 Sight , and was given a shorter 11.5 - barrel , but later it was giving a longer 14.5 - inch barrel for the bayonet and the M203 Grenade Launcher . The second model was made in May 1986 , and it was tested from May 1986 though May 1987 , at the time it have a A2 Upper Sight , and it have the M16A2 's 1 : 7 inch rifle twist , to use the heavier 62 - grain M855 rounds . The extended barrel improved the XM4 's ballistics , reduced muzzle blast and gave the XM4 the ability to mount a bayonet and the M203 grenade launcher . The XM4 was also given the cartridge deflector , as well as other minor refinements . In May 1991 , the XM4 was renamed to the M4 , and Colt made a manual . In 1994 , the U.S. military officially accepted the M4 into service to replace M16A2s in certain roles . The M4 carbine has also replaced most submachine guns and selected handguns in U.S. military service , as it fires more effective rifle ammunition that offers superior stopping power and is better able to penetrate modern body armor . </P>
when did the army switch to the m4
when did the army switch to the m4
1994
1994