Why do the military use the 5.56x45mm NATO as there standard round over the 7.62x51mm NATO ? ?

Question

Why would you use a 5.56x45mm for a military rifle when a 7.62x51mm has more range and killing power?

Answer 1

Weight vs. size; the 7.62mm NATO cartridge is nearly twice the size and weight as the 5.56mm NATO cartridge thus one can easily carry twice as much 5.56mm ammunition as 7.62mm ammunition into combat.  

Most 7.62mm NATO rifles were configured for a basic load of 100 (Four 20 rd. box magazines in ready to use storage cases and one in the weapon) rounds plus a reload bandoleer of 60 rounds for a total of 160 rounds of 7.62mm ammunition.

Most 5.56mm NATO rifles are configured for a basic load of 210 (Six 30 rd. box magazines in ready to use storage cases and one in the weapon) rounds plus a reload bandoleer of 100 for a total of 310 rounds of 5.56mm ammunition.

During the Vietnam conflict many soldiers who were armed with M14 rifle would double up their ammunition cases giving a ready to use load of 180 rounds and carry two bandoleers to reload 120 rounds for a total of 300.

Soldiers and Marines taught basic rifle marksmanship with M14 were instructed to make each and every shot count where as once the M16 was adopted the goal changed to suppressing the enemy by straying fire over the area they occupied.  7.62mm riflemen tended to be better trained and disciplined marksmen than 5.56mm riflemen as indicated by the reams of footage of soldiers and marines holding their M16 rifles above their heads, out of the line of vision and straying in the general direction they assumed the enemy was attacking from...  

Answer 2

smaller bullets are cheaper

Answer 3

Congress decided that the average American Male could not be trained to effectively fire .30 calibre weapon: that's one of the myths.

Basically, the .223 is smaller, weighs less, and you can have much higher magazine capacities at a similar weight to a .308 weapon.

Carrying more ammunition means fewer resupplies. Fewer resupplies mean fewer opportunities for the enemy to intercept your supplies.

Answer 4

Smaller round = less weight=ability to carry more. More killing power isn't necessary as for every person wounded, it takes 2 people to take care of them. So wound one and 3 people are taken out of action

Answer 5

Smaller so you can carry more. You can carry 2 m16 mags or 1 m-14 (7.62) in a pouch. Standard Combat load is 7 mags,  So, I can carry these 7 mags in 3 pouches (with one in the rifle). This is of coure swith GI (general issue) pouches. Meaning Im not going to go out and buy pouchs just for the weapons system. Also the machine guns and sniper rifles are using the 7.62. So it used as a specialy employed round.

Answer 6

Because the 5.56x45mm round has enough range to shoot stationary targets to 500 yards. Which is plenty of range for a personal weapon.

5.56 weighs less so an individual can carry more ammo. Also, a lighter round means the gun can be lighter while the user still experiences the same recoil force, or having a gun that weighs the same with more manageable recoil, enabling more accurate fully automatic fire. Weight is a major consideration for unmounted infantry.

Some define killing power by measuring how much energy the projectile has, and yes, the 7.62 does have more energy. But if you shoot someone in a vital area with either round they are going to be incapacitated. In addition, the light projectile of the 5.56 tends to bounce around inside the target, damaging more vital tissue, instead of over penetrating (going straight through).

Answer 7

Lighter. And some use the 9mm.