7.62-51 = .308 winchester = Nato Round for the M-14
and other rifles and machine guns. Which would really be the prefered round for a sniper, if shooting at long range. It is also an excellent hunting cartridge.
7.62-54 = The round the Russians fire in their long guns
7.62-39 = The round for the AK-47
30 06 = Thirty Caliber slug used in the American Long Guns
in WWI and WWII and Korea i.e The Springfield and
MI-Garand (the finest rifle ever made)
All of the Above are 30 caliber. None of the above can be interchanged between the rifles they are designed for.
.223 is the round the sniper is using and is the round used in the M-16 (the armys current main battle rifle), it is also used in many sporting weapons. At less than 150 yards it causes devestating injuries as the slug will fragment and
tumble upon impact, causing massive internal injuries and bleeding. It is still effective out to 300 yards but has lost a great deal of its energy at that distance. At that distance it will incapacitate the enemy but probably not kill him which in battle is good, as it will take other soldiers to care for him.