First, a disclaimer.
This is a story based upon a computer game based upon a fantasty world. THEREFORE any and all stories based upon Fallout MAY or MAY NOT be based upon items, actions, or systems based in real life, and ANY criticism by anyone (including me, especially) that certain details of stories do not match with real life can be ignored completely.
Which means that the original poster is free to completely ignore me and my critique of his battle tactics in his story.And now, disclaimer having being made, I would like to offer a critique of your battle writing.
In modern warfare, you do NOT want to close the range against enemies who have the numerical advantage on you, and who are also armed with automatic weapons. As long ago as the American Civil War Generals discovered that one man with a rifle behind a field fortification - even if was only a log - was worth three charging at him. Even today this is still the most basic rule of thumb in firefights, taught in military schools all over the world: you need to be at least three times as strong as the enemy if you want to assault a fortified position.
When firing on the enemy, you use your fire as part of your tactical plan. Unless you are ambushing an unsuspecting enemy, or unless your firepower advantage is far greater than theirs, you will not kill off your enemy with fire alone. You use your fire to pin the enemy, to force him into a tactical situation that is to your advantage.
An example. Let us say you, as commander, see a group of friendlies being pinned down by enemy fire from a large group of enemies. What to do?
1. First, assess and quantify enemy strength ASAP. What are his numbers? What are his weapons? Has he got heavy weapons, and if so, how is he using them? What terrain advantage/disadvantage does he have?
2. Next, from your knowledge of your own strengths, form a plan to maximize your advantages and minimize the enemy's. Do you have snipers? Then order them to target the enemy's heavy weapons. Do you have your own heavy weapons? Then use them too! Or do you have short range weapons only? Then get into a good ambush position without being seen, send some of your soldiers as bait, and when the enemy charges them, rake the enemy by surprise at short range!
3. Never forget the importance of psychology and disinformation in battle. Do you want the enemy to withdraw, fearing you have the advantage? Then split your small force into even smaller ones, and attack the enemy from the rear, unexepectedly, from two or more different directions. Bluff them into thinking they are being attacked by a large force which has the advantage in firepower, numbers and postition.
This is just a tiny example of the many tactical possibilites open in battle. I hope my post has been useful. If not, feel free to just ignore it.