There are multiple ways to bring in the behaviour of a real world weapon into a video game. Some strive for realism, some for gameplay, some to optimize bandwidth and framerate load. Without numbers and tests, I cannot comment on the optimizations, and without being subjective, cannot comment on gameplay. However, I can describe what these methods are, and how realistic they are - this is still based on personal experience and probably biased (but then, what isn't). This article concerns the cone of fire (CoF) method.

To tremendously simplify recoil is to say: every successive bullet from a rapid fire weapon moves the barrel further away from the starting aim point. This is what cone of fire attempts to simulate. Imagine a very large cone with its point jammed into the barrel of your weapon; as the weapon points steadily at your target and fires, the barrel remains stationary, but the cone flares out wider and wider. Add random distribution.

Result: the bullet's path will be somewhere within the cone. As you continue to depress the trigger, the weapon remains steady, but the cone becomes bigger i.e, flares (or blooms) wider at the far end, i.e. the path's potential to veer away from true increases.

This is a very efficient system to effect, as all you have to do for your entire armoury is set the starting radius of the cone, and the rate of increase per shot. That's it (well, apart from coding the cone to begin with, a not too difficult task if you think about it). Any future weapons can be easily adapted to this system, without modeling anything like real physics and recoil characteristics for the weapon based on weight, ammo type, weather, barrel length, etc. This is a useful quality for both expansion packs and mods, both fruitful ways to potentially increase your user base. You can do enhancements such as dynamically changing the rate based on posture (so a crouched player's CoF will be less than a running one's and expand slower), or allowing the first shot to land correctly in the precise center of the CoF.

Its downfall is that it's not particularly realistic. The target is a large, random circle not particulary close to real recoil characteristics, and at large distances becomes ludicrously off-target, far more than any real weapon would, even with sustained automatic fire. The lazy implementation (even first shot is off, completely unrealistic but again, easier to implement) is looked upon with disdain by true enthusiasts of the FPS, as the random dispersal negates any use of skill. In addition, the barrel of the weapon is steady as the user fires, or moves in a predefined way that nevertheless leaves the targeting crosshairs in place (since the CoF is doing all the work of calculating bullet destination, the barrel doesn't have to move). Once again, this approach is not very realistic, as anyone who's pointed a CoF weapon at a wall only to watch the bullet decal appear radically off-center can agree.

The CoF also robs in-game weapons of their individuality, as the question of weapon choice based on type, characteristics, recoil, style etc., turns into a far simpler question: Which has the smallest CoF? While certainly gamers' weapons choice is based on a very intangible quality (how it feels) as it is, the CoF removes even that.

Chances are that if a game uses CoF, it is there for its merits of ease of adaptation and implementation, and even, purposefully, its low verisimilitude to real life (although a tight, bloom-limited CoF with first shot 100% true may be considered a good approximation of realism - after all once it misses, it doesn't really matter on which side of the target). In Planetside for example, it is used to force an equality to a genre that is otherwise sharply stratified between casual and fanatical gamers. Even a very experienced twitch gamer who can plant a bullet between the enemy's eyebrows at 500 yards has to contend with a CoF that will send his/her shots off center.