Read this it should give you some idea as to the reasoning behind volume of fire type tactics.
http://www.themilitaryhobbyist.com/blog/2009/02/suppressive-fire-in-infantry-combat/
Suppressive Fire in Infantry Combat
Published February 3, 2009
Imagine for a moment that you are sitting in a small fighting position overlooking an open range of gently rolling hills. Your company has been deployed here to prevent the enemy’s advance on your local headquarters not far beyond your current location. You’re dug in well enough with a shallow trench and perhaps some sandbags, and your position gives you an excellent view from which to protect a nearby machine gunner.
Suddenly you detect movement at the edge of your vision. Before you can identify what it is, a bullet whizzes past your head. That bullet is promptly followed by several more, some of which impact the dirt only a couple of feet in front of your face, launching small clouds of dust into the air.
Now tell me, what are you more likely to do: bring your rifle up to a firing position, carefully take aim on what now appears to be one of the several dozen camouflaged men about 300 meters away from you, and fire; or will you drop to a protected position and then start thinking about popping up to squeeze off a few rounds before dropping to safety again?
If you said you’d calmly take aim and fire, then you’re a better man than me; better than most in fact, and probably lacking in a lot of survival instincts as well.
Instinctive response
Most people, when presented with well-aimed fire against their position, will seek to take cover from the attack. They have been suppressed by the enemy attack, and this provides the best kind of cover the enemy can have: they have a 0% chance of being hurt if they aren’t being shot at, and they can advance at will.
That’s why any defending soldier, unless pinned down by an enemy who has achieved a dominating superiority of fire (far greater volume of incoming bullets than bullets being fired in return, often achieved with intense machine gun fire) against him, is going to seek to pop up to fire off at least a few hasty return shots before returning to cover. Those rounds force the enemy to drop to cover as well, and the two sides can set into a protracted shootout rather than it ending in a close-ranged slaughter of the defenders or a total rout.
More rounds on a position adds up to a better suppression effect. Due to their rapid rate of fire, machine guns are the ideal candidates for laying down suppressive fire with small arms. Rifles can do the trick as well, but one machine gunner can put out the fire of several rifleman.
Aimed, not random, fire
While a combatant isn’t too particular over whether the bullets hitting near him are aimed or fired randomly, “suppressive fire” is usually used to refer to the deliberate firing of rounds at a position rather than an individual.
While initial aimed shots at an individual have a suppressive effect and cause him to seek cover, later rounds of suppressive fire remind him that the enemy has sights on his position and cause him to want to keep his head down, allowing them to advance further to his position and putting him that much closer to being overwhelmed.
Suppressive fire can be directed at targets merely suspected of containing enemies and will largely have the same effect as fire at targets known to contain enemies, but as the volume of fire will likely be less the suppressive effect will less as well.
Bigger is better
If aimed and suppressive rifle and machine gun fire can cause soldiers to take cover, surely something larger like an artillery shell would have an even greater effect, right?
Of course it would! And doesn’t it make sense? Several bullets nearly hitting you are scary, but an artillery shell exploding even a good distance away is very unnerving. Factor in the known deadliness of shrapnel, how loud an artillery shell explosion is, and the inability for an infantryman to do much about artillery except radio for counter-battery fire, and you have some very effective suppressive fire. Attacks by aircraft have a similar effect for similar reasons.
The deadliest round that never hit you
A bullet doesn’t need to hit you to kill you. It just needs to cause you to duck down long enough for the enemy to get close enough to you, and perhaps in a flanking position. The widespread use of suppressive fire is one major reason why the “rounds per kill” statistics for modern conflicts can become so high.
Ammunition is cheap, soldiers are expensive (in more ways than one).
Tags: Infantry, Tactics
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The bottom line is that it's not individual weapons that inflict casualties, but rather crew served weapons, indirect fire weapons, and air dropped weapons. The main #1 purpose of individual weapons is to provide suppressing fire to keep the enemy pinned in place for large weapons systems, or to keep them pinned down and unable to return fire as your elements manuever to outflank/encircle them, usually destroying their positions with grenades.