Many historians consider the first modern assault rifle the WW 2 German Sturmgewehr 44 placed in service in late 1943. It used a lighter cartridge that infantry rifles of that time used and used a gas-operated action, with both semi-automatic and fully automatic firing modes. The USSR recognized the need for a similar weapon and produced the AK-47 in 1949 which was developed by Mikhail Kalashnikov. The US M-16 history is very complicated, with many problems on its initial entry in Vietnam. It took till 1968 for the M16 to achieved widespread acceptance by U.S. troops in Vietnam. The various M-16 models have semi-automatic, burst and fully automatic modes. The M16 cartridge is lighter than the previous M-1 & M-14 cartridge, but has a higher muzzle velocity. It fires the 0.223 caliber ( 5.56×45mm) cartridge and can produce massive wounding effects when the bullet impacts at high velocity and yaws in tissue leading to fragmentation and rapid transfer of energy.
It is not legal to have a automatic version of any of these or similar weapons in the US. It is legal to have a semi-automatic version of these weapons along with many other weapons which have a semi-automatic mode. Semi-automatic weapons require the pull of the trigger each time for the weapon to fire. Semi-automatic weapons run basically from 22 cal (0.22 in diameter) thru 50 cal (0.50 in diameter). How fast the trigger can be pulled and the weapon fires widely varies.
The Bushmaster AR-15, used at Newtown, is similar to the semi-automatic M-16 and is one of the M-16 clones available. The Bushmaster AR-15 has an effective firing rate of 45 shots per minute, according to an online Bushmaster manual. Generally the M-16 clones weapons use a high-capacity 30-round magazine. Larger magazines are easily available, for example the SUREFIRE 60 and 100 round capacity magazines. Let's do a small calculation here using the 100 round magazine and the AR-15 fire time, let's see it takes then 2.2 minutes to fire 100 rounds! As a reminder, these bullets produce massive wounding effects when the bullet impacts at high velocity and yaws in tissue leading to fragmentation and rapid transfer of energy. I have yet to hear a good deer hunter or even a varmint hunter reason why they need any more than a 3 round magazine!
Moving to Handguns. The GLOCK semi-automatic handgun is one of the major handguns purchased in the US, and are used by many police and armed forces. There are various versions of GLOCK with some having up to 17 round magazine capacity. On YouTube is a GLOCK model 23 with a 29 round aftermarket magazine being quick fired... it seems to have gone thru the whole 29 rounds in 6 seconds! There are also 31 round magazines for GLOCK available. If you were a policeman how would you like to have someone pull out a GLOCK model 23 with a 29 round magazine and empty the clip in your general direction in about 6 seconds? How many rounds would someone need for self defense? I suspect for self defense about 6 rounds would be more than enough, and unlimited police and military magazines. I believe your local policeman would greatly appreciate the general population only having 6 round magazines.
An initial gun control action would be to pass a US law declaring possession of gun magazines of greater than 6 [To be resolved] rounds illegal one year after passage with severe penalties for possession. It would be illegal to produce or import the larger magazines immediately upon passage. During the one year period, the US would buy back large capacity gun magazines at fair value.
This also would create jobs to produce 6 round capacity magazines!
Realistically, a new ban on assault weapons alone, would have practically nil change in the murder rate due to the large number of assault weapons already in the country. If you tried to declare the existing assault weapons illegal, I do not believe you could get enough votes to pass it, and if passed the Supreme Court would immediately nullify the law due to the existing second amendment.
But by declaring the holding of large capacity magazine illegal, and paying to buy them back, this should be legal and quickly implementable.
My message is: 'the most bang for the buck' is to support immediately the banning the large capacity gun magazines. This item should get immediate high priority to support.