What amuses me about the whole Assault Weapon Ban idea is that it is simply an exercise against ergonomics and manufacturing standards.
I mean, look at it this way:
http://www.logarchism.com/wp-content/uploads/2012/12/0815d2ed-66d9-4159-8691-0c61dce8d026-new-guns-slide-1.jpg
Collapsing stock: Primary use of a collapsing stock is to adjust the length of the stock to fit a shooter better. The basic idea is to make it easier for a person using it to accurately fire and adjust to recoil without requiring a customized stock or dealing with a one-size-fits-all stock. Main people it generally helps would be women and shooters who aren't of average (male) size and build.
Folding stock: Primary use is to reduce the overall size of the weapon for storage or carry when not in use. The basic idea is simply to allow the weapon to be where the person using it is more comfortably when the weapon isn't actually being used. If anything, folding stocks increase inaccuracy in some designs and/or increase felt recoil in designs where the conventional stock it replaces contains a recoil reducing mechanism.
Pistol grip: Primary use is to change the angle of the hand to the wrist, usually to allow a more comfortable position and reduce strain on the wrist. It also tends to increase the ability to control a weapon for people--like women--who do not have a wide grip span or a high grip strength. While some people say it's to allow "spray-and-pray" hip shooting, one of the first weapons designed to allow for "hip firing" was the Browning Automatic Rifle and (early versions) used a conventional stock. Later adaptations and many of its peers used pistol grips, but were primarily intended for use from and initially were equipped with bipods as walking fire is generally less accurate than fire from a stable position farther away.
"Barrel shroud": In the "basic" form, simply a ventilated barrier between a chunk of metal that gets hot (because you have put burning gases through it) and the rest of your body/hands/etc. Sort of like the grill on a space heater to keep you from touching things that will burn you. Other "more advanced versions" may allow the attachment of things like lights (so you know what you're aiming at) and sights (so you don't hit what you aren't aiming at).
Flash suppressor: Primary use is to turn a large fireball at the muzzle (depending on the barrel length/ammunition combo) into one where you aren't trying to shoot blind after each shot. Simply, it allows a shooter to continue to identify targets/non-targets as well as not disrupt other shooters' vision. You don't typically see these on pistols because the type of powder used is usually consumed quicker reducing blast. You often don't find these on shotguns for the same reason and on long-range hunting rifles because the barrel is longer to allow greater power and accuracy.
Bayonet lug: Original use was to attach a bladed, melee weapon to your rifle in case you ran out of ammunition. Currently, most of these are more collector items than the weapons that can fit them as well as the US barrel length requirements often making bayonets no longer able to securely attach to a weapon. This currently exists--primarily--due to manufacturing standards for the various parts (front sight assembly, gas block, muzzle device, etc.). For manufacturing, the availability of standard parts shared with military models--but not parts of the fire control mechanism--often drives the presence of these.
Although not explicitly listed in most lists, the general appearance or "black rifle" look is generally based on manufacturing standards. In most cases, "assault weapons" are black due to the finishes applied and the lack of concealment of various parts by wood. Generally, this is to allow these firearms to meet requirements regarding rust-resistance, resistance to various oils or acids, as well as to decrease shine on the weapon.
The use of wood--historically--was dropped for most military weapons because of susceptibility to humid climates, reduction of weapon weight, and simply the added cost and time to produce while being difficult to reliably meet production standards. The resulting designs--primarily of metal and plastics--also allows more modular, reliably interchanging parts between those weapons produced to the same specifications. Sort of like the parts of a modern car.
The problem with the specifications banned is not address the lethality of the weapons or their actual use. In order to protect hunting, lethality can only indirectly be addressed through ammunition capacity because most traditional hunting rifles (and shotguns) are more powerful than most "assault weapons" because the focus for these weapons is usually on ergonomics and manufacturing standards more than lethality. Even addressing the magazine capacity--itself an ergonomic compromise between weapon weight (loaded) and how frequently magazine changes are required for the same number of rounds fired--is only applicable in theory to the first magazine fired's total capacity and should actually not matter if any time at all is required during a fight to do something like move or locate a target.
In these cases, the ease of reloading--another ergonomic measure--reduces the limits on lethality based on magazine capacity.
Overall, however, I think the actual result of passing such a war on ergonomics and manufacturing standards without directly addressing the behavior of criminals is more likely to simply push development of decentralized manufacturing of weapons as well as "parallel" lethal technologies like pneumatic weapons to which many of these rules might not apply. Additionally, with the protection of older, more lethal weapons, the ongoing design and production of more ergonomic "chassis" to install older weapons in--like those for older M14/M1A rifles and even M1 Garands--will likely continue and exploit the lack of focus of this sort of legislation to create weapons just as lethal and nearly as ergonomic while missing the opportunity to address the criminal behavior behind these mass shootings.
It doesn't take a gun to kill a lot of people. It doesn't even take a well-designed one either.
