The 5.7x28 is 5.62 at the grooves.
The 5.45x39 has 5.62 bullet.
Or Yahoo answers [faceplant]
The 5.62mm round is a NATO round used by NATO forces. This isn't the only round in the military arsenal. Sniper weapons like the M82A3 is a .50 cal weapon that is accurate over 1.5 miles and will pentrate concrete. It really depends on your mission. a 5.62 FMJ round, is completely adequate for infantry regulars and has a higher magazine capacity as well as rate of fire as well as muzzle velocity than a 7.62 round (which we also have in our arsenal as well). The M249 SAW as an example. The Mark 16 SCAR is used by special forces in the US Military and is an exemplary 5.62 weapon.
As far as your question goes, only with heavy body armor including ceramic plates and a distance would a 5.62 round not penetrate a troop . It's stoping power is substantial.
Master Gunnery Sergeant, USMC, (Ret.)
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