Ah, yes! The old 7.62mm vs 5.56mm controversy surfaces again!
Gentlemen, The US Military Establishment spent many man-hours, years or study, and tens of millions of dollars thoroughly researching the pros and cons of adopting the 5.56x45mm NATO and 9x19mm NATO calibers.
The simple fact is that 5.56mm NATO offers much more than 7.62mm NATO infantry weapons do. Namely:
1. 5.56mm ammunition takes up less than half the weight and space that the equivalent amount of 7.62mm ammo does. The individual solder's firepower has been greatly increased.
2. Killing and wounding potential are only slightly related to incapacitation capability. The military regards incapacitation of an enemy soldier as being more important than simply killing him. It takes two or more soldiers to carry or care for one badly wounded man. That drains enemy resources in warfighting more than simply killing an enemy soldier.
3. The penetration and wind drift characteristics of the current 5.56mm ammunition exceeds that of the 7.62mm ball ammo. It is greatly superior (hit capability, firepower, sustained fire support, etc) in the SAW platform than a similar 7.62mm weapon.
4. Logistics support for the 5.56 NATO (ammunition resupply, weapons repair and support, spare parts, training, etc) are too well entrenched to easily replace the M16A2/M4/M249 series weapons.
5. The 5.56mm M16 series is now our longest-serving service rifle. It has surpassed the grand old M1903 Springfield's 36 years.
6. The Israeli Defence Forces, Republic of South Africa, have/had a continuity of battle experience (GENERATIONS of fighting), and neither wanted or needed 7.62mm infantry rifles. They consider the 5.56mm a superior anti-personnel caliber.
7.Almost all of the US-supported central American and Far Eastern militaries now use the M16-series weapons. They previously used .30-06 and 7.62mm weapons and are equally happy to have the latest in effective infantry weapons.
8. The former Evil Empire (Soviet Union), now Russia, saw the light and started to transition to the 5.45mm caliber AKS-74 weapons. Their ammunition has about the same capability as our 1960's 5.56mm M16A1.
I, like many of you out there like and prefer the good old steel-and-walnut "he-man" classic calibers .30-06, 7.62mm NATO, .303, 8mm, etc. But the simple facts are that the world's most established, numerous, and effective small arms weapons use the 5.56mm NATO wether we like it or not. It, or a minor variation, is likely to remain the standard military rifle caliber for many more years.