ORIGINAL: JeffK
It doesnt have to be bolt action, the Self Loading Rifle (FN FAL) used by Australians in Vietnam and up to the Steyr being used was a far better Infantry weapon than the M16.
Firing single shots makes the soldier think and aim, have auto fire sees them (natuarally) want to get off as many rounds as they can.
Plus, IMHO, the 30cal/7.62mm/.303 round is far more lethal than the 5.66mm. So what if I carry less ammo, I'll be more careful with it!!
The Marines stress "fire discipline and fire control" - and note that you need to end each firefight "with enough ammunition to fight and win another firefight if you are not resupplied." Further, they believe that not carefully expending ammunition leads to very ineffecient tactical effects. The Marines also train on the basis that they expect to be outnumbered and outgunned, and flanked ("defend 360" is the norm even for the smallest units) - and the ultimate expression of this doctrine is its application to naval landing parties (which in the post war era became standardized as independent squad sized organizations). No matter the mission - you get 14 men (or 15 if they attach an officer).
These need to go there, do that, and return, no matter the size of the opposing force, no matter the details of the mission.
The focus is the mission - and not on fighting for its own sake. It may be counter productive to engage an enemy unit - and there are lots of reasons for that - starting with ammunition expendature and the risk of casualties. [Each casualty greatly impacts your mobility and the possibilty of mission failure] While a naval landing party has some significant advantages over normal infantry squads - including
1) it is composed of specialists, and has its own radio operator, its own medical corpsman trained to higher than Army standards, and typically gunners mates and specialists of other sorts - so it has more techincal prowess than is normal in a squad
2) it can call on heavy firepower in the form of naval gunfire support or naval air support - because normally at least several - and possibly all - members are trained spotters
nevertheless the key factors to success are psychological rather than physical (or arms as such). The significant points here are
1) Trained to Marine standards, these infantry EXPECT to be outnumbered WITHOUT friends on the flanks and in rear, and this does not disorient or demoralize them;
2) Trained to focus on the current mission, these infantry do not engage any enemy without mission oriented cause or as a last resort when the mission has failed; this focus inherantly supports fire discipline and limits ammunition expendature and combat risks - mitigating the "behind hostile lines" and "no supporting units" aspects of the situation
3) Trained to work with just a few weapons, not including even hand grenades, and in company with the specialists who care for those weapons all the time, they tend to understand all the tactical options associated with them; The Marines explicitly teach "it does not matter how modern the weapons are, but rather how familiar you are with them and how well you use them."
