There are several different values which are used to calculate how good a weapon is. Below is an explanation of the statistics.
This is the maximum damage that the weapon can do to an enemy. The actual amount will vary considerably, the minimum always being 1. A normal soldier has 100 hit points. Some weapons can cause very high damage and gain 1-hit kill capability due to this. Other weapons can at best cause only severe injuries and require multiple hits to eliminate the target.
Range is how far your weapon can fire effectively. The range is measured in pixels. As a guide, the screen is 450 pixels long by 550 pixels wide. Range can be limited by Line of Sight. Within effective range, a Ranger will have maximal combat efficiency.
Determines the amount of rounds fired at a target within given time. Generally weapons with high fire rate consume ammo far faster and can be more wasteful as killing weapons while excelling as fire suppressors. Weapons with low fire rate on the other hand usually are more accurate with higher killing potential.
The amount of rounds in a single clip.
How long it takes in ticks to reload a weapon. Ticks are a measurement of game time used to decide how long things such reloading last. 20 ticks are equal to 1 second. For bolt-action rifles, you must reload after every round.
Determines how heavy the weapon is. Higher bulk weapons increase the weight the Ranger is carrying and results in potentially far more noise. Low bulk weapons are more ideal for silent reccees.
The chance of a weapon jamming when firing. In case of a jam, the weapon must be cleared before it can be operated again.
Number of Clips
Amount of clips the Ranger carries with the weapon. More clips allows for longer combat orientated missions.
After every round fired, the Ranger suffers an accuracy penalty when firing consecutive shots within a burst. The effect stacks during the burst, for example, a 5-round burst with Stoner 63 which has recoil of 5, will have 20% accuracy penalty when firing the 5th shot.
The distance within where all infantry units are instantly killed and blown to bits and pieces. Only seen on weapons utilizing explosive projectiles.