The 5.56 is a fantastic service rifle caliber. With the advent of the newer Mk318 and M855A1 it is even better. It has low recoil, low weight, accurate, and works very well in the normal combat distances of under 300 meters.
Here is my basic carry load for the invasion of Iraq in 2003 when I was a SAW gunner. Thats 900 rounds of linked ammo. With that ammo, my vest, my gun, water and other miscellaneous crap my gear was right around 96 pounds. That doesnt include my ruck.
Everyone talks about the lack of lethality of the 5.56 at range. I will agree that it lacks good punch at range but it still is effective and I have a story for that. But the fact is that the vast majority of Soldiers and Marines are not making solid if any hits at that range. The enemy isnt standing out in the open wearing orange hunting safety vests. They tend to hide and use cover and camouflage.
Adding the ACOG to the rifles and carbines had made a huge difference.
Story: Note this story is about combat in Iraq in 2005.
In 2005 my unit was in eastern Iraq near the Iran border. We had a mission to escort high ranking officers to a meet and greet in a small farming town in our AO to offer aide and money after one of our Abrams had run over a bus and killed several locals. It was the bus drivers fault by the way.
So my platoon is tasked with outer security around the town which was surrounded on three sides by canals. I was on a hill on the outside of the town and was able to over-watch almost one whole side of the town. they had me there because I was a squad designated marksman and had a modified M16A4 with a stainless fluted free floated barrel, an ACOG, and M262 77 grain OTM ammo.
Towards the end of the meet and greet an Iraqi Army patrol drives by in some Toyota and Nissan gun trucks. They pass my position and start heading down the road alongside one of the canals. The patrol was hit by an IED and begins to take small arms fire from a wooded area inside the town alongside the canal. They engage in a fierce firefight back and forth across the canal.
I follow the IA tracers back to the wooded area and see some guys by a building. i should point out that the IA, the insurgent position and my position were laid out like a L shape with the bad guys in the middle. As they engaged the IA the insurgents gave me their flank.
earlier my team leader, who was with me, and I had estimated the range to the town wall, which was a rather low 2 to 3 feet, at around 350 meters. I look through my ACOG at the guys in the wooded area and see that they are firing AK-47s at the IA as well as directly 180 degrees towards some other soldiers in my platoon who were manning a check point approximately 300 meters away. Those soldiers were busy fighting other insurgents as this was apparently a planned attack with multiple ambush/fighting positions.
I take aim at the easiest guy, he was standing still, who was firing at my friends. I placed the 300 meter line of my ACOG at high chest and squeezed off the round. The bad guy fell instantly to the ground. Another bad guy stopped shooting and ran up to him and started dragging him back into the woodline which was slightly up hill. As he was dragging the guy away I shot off a few more rounds which missed. As the bad guy was being drug away I could see him holding his stomach. They got into the woodline so I started engaging other targets that popped up. I made no more hits as the others got wise and started moving about. Shortly after they retreated into the woodline and merged back into the population.
During the AAR we measured the shot on a map and found it to be 400 meters +/-10. We had killed 3 enemy that day including one that had a single shot through the abdomen near the belly button. A misjudgement of distance caused my shot to go low but the heavy 5.56 still took the bad guy out of the fight.
Pic of me and my rifle in 2005.