Quote Originally Posted by Ken White View Post
rapid -- not necessarily automatic weapon -- fire in some ambush counteraction or surprise situation. However, in my observation, there's no 'rule of thumb' as to when and where to use the technique. Each situation and terrain set poses variables. For example, in a jungle setting, a turn into the ambush positions and rapid semi-aimed (never spray and pray -- so jcustis is also right IMO) and an assault will often be beneficial.
Yes in the main but... IMHO you can't leave it to commanders down to fire team level to figure it all out in the heat of the battle.

For guidance we look to the Brits:

From Land Operations Part 2 - Jungle (code 70736 - part 2) we get:

Immediate Action Drills Troops moving through close country are likely to encounter the enemy very suddenly at very short range. To ensure that they react immediately and sensibly and to give the commander time to carry out a quick battle appreciation, immediate action drills must be laid down to allow for contact with the enemy from any direction. The drills must be:

a. Simple So that they can be clearly understood by every man and carried out automatically without any further orders.

b. Immediate So that the enemy is caught off balance and the the initiative is regained or exploited.

c. Aggressive In order to inflict the maximum casualties and retain or gain the initiative.
Working from this base the Rhodesians formulated/developed/refined Encounter Actions as follows:

The Encounter Actions

1. It is important to note that although encounter actions are usually taught on a section basis, they can be adopted for use by a platoon. These actions are applicable to the varied forms of terrain and in all cases normal infantry minor tactics or section and platoon battle drills usually apply after the initial contact. These encounter actions are a sound framework on which leaders at all levels should build as their experience dictates. it should be remembered, however, that no action, drill or order will achieve success unless the leader and men have practiced them to a stage of instinctive action, reflex and immediate reaction to firm and confident initiative on the part of the leader.

2. If a patrol is accompanied by persons who have little or no knowledge of encounter actions, e.g., guides, informers, surrendered terrorists, etc., the patrol leader should keep them strictly under control and in his view. These persons should be briefed as thoroughly as possible before the patrol starts. It may prove as well to rehearse encounter actions for these persons or even for inexperienced troops before a patrol moves out on operations.

3. Encounters with enemy could fall under one of the following headings:

Situation A. The initiative is with the military forces (terrorists seen first). Reaction: Immediate ambush.

Situation B. The initiative is split between the military forces and the enemy (simultaneous sighting). Reaction: Immediate offensive action.

Situation C. The initiative is with the terrorist (military forces are fired on with small arms or are ambushed). Reaction: Immediate offensive action to an enemy ambush.
Read more here

With (combat) experience commanders can develop and refine this drills to suit local conditions (enemy and terrain). And by experience I mean experience and not only having been on the receiving end of the odd angry shot.