As far as Illegal weapons go, The selection here is much wider due to its proximity to other less restricted countries.
This of course is a main reason why gun control demands more gun control. Every nation that has restricted arms wishes to impose the same or more restrict laws on thier neighbors whether they are other states or other nations. You see it across the board, "Our gun control was becoming such a great success, but ______'s (other nation,state, locality) lax gun laws ruined it by giving people a way to circumvent our control. So we demand more control from these places, don't they care about the children...?"
The truth is that it has always been the business to import from wherever they are available. It is done with drugs, it will be done with firearms. With demand supplies will be found. Even if the entire world had strict gun control, some lone elements would still make them, and wars would still be fought where many of the arms legaly necessary for government would end up in private hands to end up on the black market. There would always be police and military someplace in the world willing to sell arms to others, or with corrupt members that put some of those arms in the hands of criminals. Unfortunately law abiding people would be utterly defenseless against both these criminals, as well as thier government's storm troopers that could implement any policy or genocide or mass arrests/imprisonment's with little immediate resistance.
It could even be argued that the availability of arms in the U.S. is a retarding factor to the illicit weapons trade there.
It is most definately the reason why the government has control over the majority of arms and the type of arms sold in the US. In the UK the arms that can be bought are numerous and since they are all illegal, full auto firearms are more available than ever. You can purchase a submachinegun or a handgun, your choice, just as easily.
Now if you look at the US the types of arms available and in general circulation are predominantly what the government approves of. This is because legal avenues are provided to easily purchase these arms. These include semi auto firearms of all types, and complex firearm laws that keep agencies like the BATF employed giving them free reign over the firearm owning population allowing them through the pretense of scrutiny of these laws to inspect any premises or investigate any firearm owner.
So technicaly it can be argued that by allowing most citizens legal firearms, you can control the types of firearms present. Of course there is a limitation on this. If the firearms available become so handicapped as to be insufficient to the criminal elements that will still attain them just like anywhere in the world, then they will go through the trouble of importing thier own, which will then be outside the influence and control of the law. However what is handicapped for a private legal owner, like a side by side long barreled shotgun, is quickly converted into a short barreled, stockless firearm little bigger than a handgun for use by criminals. So even the least menacing firearm suitable for hunting can still become deadly criminal weapons (as is widely seen in places like Australia now.) So gun control does not work for the purpose it is sold to the masses.
So while most of us do not support gun control, and this side "benefit" of legalization is not appealing to me, it exists nonetheless. IN A NATION WHERE FIREARMS ARE FREELY AVAILABLE AND LEGAL, THE TYPES OF FIREARMS GENERALY IN CIRCULATION CAN BE LEGISLATED AND CONTROLLED. IN PLACES WHERE THEY ARE GENERALY ILLEGAL, THE TYPES OF FIREARMS IN CIRCULATION ARE THOSE WHICH ARE THE MOST DESIRABLE TO IMPORT.
For example in our nation they can create retarded laws like assault weapon bans, and those firearms in general ceased to be sold. People with money they wanted to spend on a firearm bought something that complied with the laws, and thus the government actualy had control over what the people were arming themselves with. In the UK you have no control over whether they are armed with handguns, or bulk numbers of AK74Us imported from elsewhere. Firearms that are compact, cheap, created en masse and fully automatic. You also have no control over the types of ammunition sold. Armor piercing, incendiary, explosive projectiles, even poison rounds can be traded just as easily as any other. They have lost all control over what is possessed by thier population.
So widely legalized firearms actualy coincides with gun control more than a total ban. With a total ban people no longer decide if they want to risk getting in trouble breaking the law to have a slightly different firearm, or just enjoy what is legal. They get whatever they want because it is all illegal anyways.