It's sadly low in combat due to the chaos and lack of time to engage properly. It's similar to the police. It's something like 18-20% direct hits. What people who have never been military or police may not realize is that when your body goes into fight/flight mode, you lose your fine motor skills for gross motor skills. This is a very real thing. Training can compensate for this to a degree, but doesn't remove it. As the Corps used to say: "The more your sweat in peacetime the less you bleed in war." Also a person falls to the lowest level of training they have received during an incident. If you have developed great muscle memory and train hard, you should do fairly well. So many things come into play: learning how the weapon operates normally, how to tap/rack/bang, clear malfunctions, magazine changes, weapons maintenance--all these play a role in how well troops do when the chips are down.