One way arguments are obfuscated (as we recently saw in discussing what "marriage" means) is by using terms without defining them. We might be in part guilty of this, as in a previous article we noted that "assault weapons" were almost never used in the type of shootings on which gun control advocates base the arguments for banning them, but we did not define "assault weapon". A similar problem arises in regard to "automatic" and "semi-automatic" with reference to guns; this hopefully will clarify these terms.
An "assault" weapon is one designed fundamentally for use in close combat. It has a shorter range and generally a lesser impact than rifles made for hunting, or sniper rifles; often it has a bayonet fitting, on the assumption that the person using such a gun is in the middle of the melee and at times will be as easily able to stab his opponent as shoot him. Such weapons are usually (but not necessarily) "automatic" or "semi-automatic", allowing reasonably rapid fire rates. The designation is vague enough that the traditional "six gun" revolver could qualify, as it is designed for close quarters fighting and rapid reset for the next shot.
The definitions of "automatic" and "semi-automatic" are a bit more difficult. Some suppose that any weapon which reloads itself after firing a shot is an automatic weapon, but although a revolver does exactly this it is not considered to be in these categories. Some assume, again incorrectly, that the requirement is that the weapon ejects its shell casings. For an "automatic" weapon, it is assumed by some that rapid continuous fire is sufficient to qualify, but a Gatling Gun produces rapid continuous fire, ejecting spent cartriges and loading new ones, and is not considered "automatic".
What makes a weapon "automatic" or "semi-automatic" is a strictly mechanical aspect: it uses part of the energy from the explosion which propels the projectile to reset the weapon for the next. If it is "semi-automatic", it does no more than that, requiring that the trigger be released and pulled for each shot; if it is "automatic", the trigger may be held, and the mechanism will fire the next bullet once it has been chambered. Some "automatic" weapons have a "burst" setting, which causes the weapon to fire usually three to six rapidly consecutive shots on a single activation.
Fully "automatic" weapons are already restricted from civilian ownership. In seeking to ban "semi-automatic" weapons, advocates are targeting primarily the pistols in common use by law enforcement and private security agents. Rifles which require the user to operate the cocking mechanism by hand, revolvers, most shotguns, and of course Gatling Guns would be permitted. Note that standard hunting rifles, shotguns, and Gatling Guns are neither "assault weapons", as they are considerably more powerful and not designed for close fighting or self-defense, nor "automatic" or "semi-automatic" weapons, because they do not use the power of the shot fired to chamber the next round.
At issue, then, is whether banning such weapons would have any impact on shooting deaths, or particularly on the kinds of shooting deaths which are cited in support of such bans. We might decrease the number of semi-automatic pistols in circulation, but in all likelihood the owners would replace these with revolvers, and gun manufacturers could easily design guns that fire and reload rapidly without using explosive force to drive the mechanism--electric guns already exist, but are not in popular use because semi-automatics are simpler. One thing that designer drugs have taught us is that any battle against current technology is bound to lose as new technology supercedes it. We can ban "assualt weapons" and "semiautomatic weapons", but these will be replaced by other technologies that do the same job, probably more effectively.
And, as has been demonstrated by many accounts, making guns illegal only keeps them out of the possession of people who would use them legally.