In Iraq, there was a lot of infantry fighting, and reports are coming back about the performance of various infantry weapons. The 5.56mm round used by most coalition infantry rifles had no trouble knocking down enemy troops, especially if they were hit in the head or chest. Hits in arms and legs were less likely to stop the bad guys, but this has always been the case with infantry rifles. Some troops asked for the heavier, 77 grain, 5.56mm bullet, rather than the current 62 grain bullet in the NATO standard SS-109 5.56mm round. Debate over adopting the 77 grain bullet has been going on for some time. Some Special Forces troops are thought to have been obtaining 5.56mm ammo with 77 grain bullets for their M-4 rifles and using it in Afghan and Iraqi operations. The heavier bullet is supposed to be more likely to knock down men it hits.

In Iraq, the average range of engagement for infantry was under a hundred meters, more often 20-30 meters. Even the snipers rarely took a shot farther than 300 meters. A lot of thing fighting was in urban areas, where the Iraqis preferred to stand and fight. This raised two more issues. The infantry want more pistols. There were many situations in buildings where a pistol was a better weapon than a rifle. Also, more pistols in the infantry (at least one or two per squad), provided back up weapons when rifles or machine-guns broke down. It was also noted that many of the 5.56mm M249 squad machine-guns, first introduced in the early 1980s, were wearing out. The M249s got a work out in Iraq and many literally fell apart, especially among the Marines. But the Marines were also quite happy with their new 7.62mm M240 machine-guns, which they had just received to replace their ancient M-60s. The army had adopted the M240 years ago and both services use the M240 on vehicles and as a "medium machine-gun" in infantry units. The heavier bullet of the M240 came in handy in city fighting, where you often wanted to shoot through doors and some walls. 

Support troops, and crews of armored vehicles, wanted a small weapon than the M-16, and many mentioned the M-4 (an M-16 with a shorter barrel, 33.3 inches long overall). But even infantry complained about the length of the M-16 (40.3 inches) when operating in cramped urban environments. Some troops used captured AK-47s (34.5 inches long) for city fighting.

The 9mm pistols continued to have problems. The big one was weak springs in the magazines, which tended to cause failure to fire, and the tendency of bullets to fall out of magazines not loaded.