Actually bayonet charges were not only used when out of ammo, but certainly this was a factor.

I recall in the book: Tales by Japanese Soldiers of a number of occasions..esp at night where Japanese infantry were told to empty their rifles!!! in preparation for night charge.

While this seems counter intuitive (and honestly i think its silly), but the idea was that no one would accidently or through fear fire a round early and alert the Brit forces of the eminent attack.

This was another technique used by Japanese inf to negate Allied superior firepower. Night bayonet attacks were in a strange way a good technique..when it worked..as trying to rush MG positions in the daytime wouldn't work.

There is much made of "Japanese suicide" attacks..but only in a few occasions were they truly intended to end the lives of the Japanese...the idea was to kill the enemy..even if the idea was technically flawed cause the enemy had many MG's. Really only on the island campaigns where it was clear there was no escape, no retreat and no hope for re-enforcement do you see what can fairly be called a "mass suicide by mg".

Its interesting though how we characterize the Japanese actions as "suicide" charges and when allied nations fight to the last man we think of it as a "heroic" last stand.

To me its a little like the idea that all Russian troops were simply feed into the German MG's in solid waves of human fodder. While this happened it really wasn't the norm. Its also a lot like the idea that every Tiger simply drove up killed 10 Shermans and went home.

What is amusing is how a few of these incidents have become so famous that we consider it the norm now.