One thing is clear the high-powered rifles capable of shooting multiple rounds in a hurry are in high demand.
Anyone who says the rifle used in he Connecticut school shooting last week is high powered or an assault weapon is functionally illiterate in respect to firearms.
One of the major criticisms in military circles in regard to the 5.56 mm NATO round used in the many variants of the M16 (M4 civilian model used by the shooter is a M15 variant) is that it is under powered and has limited range in comparison to other military issue weapon in service in the world.
An assault weapon is a full auto or burst capable rifle which the civilian model M4 is not.
Reporters worthy of the title should make some effort to get their facts and their terminology straight when attempting to write a story.
The burst or automatic mode in military rifles is pretty much irrelevant as to the deadliness of these rifles. Auto fire modes are intended to be used for suppression of enemy troops - basically scaring them into keeping their heads down and not shooting.
If the government were to permit these to be sold in full-auto versions I doubt there would be any increase at all in casualties from these weapons. The few additional bystanders hit would be counterbalanced by fewer intended targets hit.
The killing/wounding mode is semi-automatic. These rifles are efficient killers because they are capable of very rapid aimed fire, a use which is easy to teach because of low and well-handled recoil. The large ammunition capacity and the magazine system is the second critical factor. Accurate fire can be sustained over many targets without requiring a magazine change. Magazines are also rapidly changed.
For the purpose of killing people these give a great increase in effective short-range firepower over most semi-automatic civilian rifles, that generally use over-powered ammunition and small magazines.
This great firepower also makes these rifles constitutionally relevant precisely because they are militarily effective. They make excellent guerrilla weapons for a “well regulated militia”, at least under modern urban conditions. They are less effective for the purpose of offensive combat against regular soldiers as they are less capable of suppressive fire, but are excellent for ambush or hit-and-run tactics.