ARFCOM team, longtime lurker & seldom poster here: I just thought I'd cut & paste the text of a letter I wrote to my reps using the NRA-ILA's "write your reps" tool.  I had to make a pretty concerted effort to keep from expanding on too many points; my goal was to have a realtively short (in this case 1 1/2 page) letter that hit all the major points (from my perspective) on this debate.  Feel free to take it and use it as your own:

 I am writing you concerning the recent push for new Gun  Control regulations.   The proposed Assault Weapons ban, ban on “High Capacity” magazines, and requirement for universal background checks will likely be brought forward for action by political representatives such as yourself.   While some of the new measures’ supporters may have only the honorable intention of reducing crime, these new proposals are both ineffective and tread heavily on the freedoms of all Americans.  
 Firstly, the actual term “assault weapon” is highly misleading and inherently flawed.  The “assault weapons” referred to by today’s politicians were never manufactured as such; rather they were- and are- perfectly legal, semiautomatic firearms.  The term “assault weapon” is a constantly shifting label applied retroactively to firearms that, in many cases, have been in legal production for multiple decades.
 Gun control proponents will often invoke rhetoric centered on keeping “weapons of war” off the streets.  While the weapons currently at the center of our gun control debate or not “weapons of war”- as they lack the capability to fire automatically- it is worth nothing that there is a substantial precedent for the civilian ownership of weapons developed from military initiatives.  Put simply, since the dawn of firearm technology it has been nations’ military interests that led to most- if not all- firearm technologies.  This in turn led to rifled barrels, the brass cartridge, lever-action rifles, revolvers, bolt-action rifles and, finally, semiautomatic firearms with detachable magazines.  All of these technologies have been employed in the design of civilian-legal firearms dating back to prior to WWII.
Also of significant controversy are the “high capacity” magazines that are used to operate these firearms.  As with “assault weapons”, these are items that have been in legal production for several decades (dating back to at least the 1930s, if not earlier for some models) that are now the subject of a retroactive categorization.  In truth these are not “high capacity” magazines, but standard capacity accessories that are used lawfully by millions of gun owners.
 Given the widespread, lawful use of firearms incorporating all these various technological design features, it should further be noted that the portrayal of “assault weapons” as unusual weapons not used for “legitimate” purposes is wholly untrue.  These weapons are among the most popular firearms in the US today.   Semiautomatic, detachable magazine long guns (rifles) and handguns are used every day by law-abiding citizens for personal protection, target shooting, hunting, and competitions.
Supporters of renewed gun control often cite their support of hunters and sportsman as evidence of their respect for the Second Amendment.  In light of this one should remember that- despite the not inconsiderable debate often surrounding the Second Amendment- that it in no way refers to hunters, sportsman, nor the sporting use of firearms.  As such it would be reasonable to disregard all opinions voiced by such an individual, as they clearly choose to disregard even the most basic facts at the core of this debate.  
  Finally, universal background checks are also an inherently flawed proposal.  The “gun show loophole” does not exist; state and federal firearm laws apply regardless of the location of a sale.  Private individuals cannot engage in the business of selling firearms and must follow state and federal laws when conducting private sales of personally owned firearms.  Violation of those laws should be met with legal persecution- not the introduction of additional laws which will only apply to those law abiding citizens already inclined to follow such regulations.
 Gun control in America has a long, established record of being an ineffective policy in the pursuit of public safety.  Approximately every few decades a new proposal is offered to the American people as “the” solution to gun violence; each proposal treads more and more heavily on our Second Amendment rights.  The National Firearms Act of 1934, the Gun Control Act of 1968, the Firearm Owners’ Protection Act of 1984, the Assault Weapons ban of 1994, and now the new gun control proposals we are currently facing all clearly show this trend.  Additionally, the tragedies suffered by our country within the past year such as the Connecticut shooting were the actions of deranged, mentally unstable individuals that are not representative of the American firearm owner.  For each one of these horrific crimes carried out by an individual madman there are literally millions more citizens who own “high capacity magazines” and “assault weapons” who solely use their weapons and accessories for legitimate purposes .   Those who wish to do evil will find a way to do so regardless of the legality of their tools, or the configuration of the firearms that they obtain.    
 The Gun control measures currently being proposed will not make our country safer, and will only continue to violate the rights of all Americans.  As your voting constituent, please consider this my official request that you vote against the introduction of more ineffective legislation.