Guns are symbolic of aggression and harshness. The gun can...
One of the symbols in "The Sniper" is a gun. We see two different versions of it, handled by two separate, opposing forces. The first sniper has a revolver and a rifle; the second sniper has a rifle.
Guns are symbolic of aggression and harshness. The gun can obviously symbolize the need of someone to protect oneself or another. Some sources say that the gun can symbolize almost anything.
With this in mind, it is important to look to the characters that use the guns to ascertain what the gun means to each man.
Our first sniper uses his revolver at first, but seems to become more aggressive with the rifle in hand; he is cynical and angry. He uses his gun to destroy, and does so without discretion or a sense of humanity. Although he is fighting for a cause, this seems perhaps to be more a justifiable reason to fight and release his aggression than to protect some ideal.
We know that the sniper is furious. We can assume it has to do with the war, but we also know that the sniper and his brother have parted ways, each on the other side of the conflict. This may have caused a sense of betrayal in the sniper, which is a loss of control. He has become fanatical, the narrator tells us, so we can assume he acts impulsively, without conscience. The revolver is a small arm, which might represent the sniper's involvement to a smaller extent in the early moments of the story. When he can no longer make use of the revolver, the rifle becomes an extension of his rage, and he indiscriminately uses it to even kill the old woman. His justice is swift and makes no distinctions. He has gone beyond dedication to a cause, and become a killing machine.
With less information on the other sniper prior to the story's end, we have less to work with in terms of his personality, but we know he, too, is dedicated to his cause. If the first sniper is so radically oriented, we can assume the sniper on the other side is not fanatical. He is diametrically opposed to the first sniper; calm, calculating, focused, and patient. He seems to have more self-control. His weapon is symbolic of his dedication to his cause, not in terms of aggression, but for the protection of his country and himself.
When the first sniper drops his rifle, he does so to lure his opponent out into the open. At this point, he releases the urge to aggressively pursue the other sniper and becomes furtive and sneaky. He sacrifices the control he feels with the rifle to gain an advantage over his opponent. Without the rifle, the sniper must return to the revolver, stepping back to gain, literally, a better perception of the situation in order to take out the other sniper.
When the first sniper's rifle falls, this indicates to the second sniper that he has wounded or killed the shooter across the street. Logically, these would be the only reasons a sniper would release the control of the rifle, the weapon most able to find its target with accuracy, across the space that separates them. In this way, the second sniper is killed when he reveals himself. His loss of his rifle symbolizes his loss of control, his protection, and literally, his life.
Separation from the rifle seems to bring the first sniper back to reality. He immediately suffers from feelings of remorse, and becomes so enraged that he throws down the revolver, cursing all war, and nearly shoots himself in process.
Perhaps his reaction is an example of foreshadowing: it is at this point that the first sniper discovers the identity of his adversary.