Paul,
Define "assault weapon" for us.
Contrary to what some folks think, assault weapons are not readily available here in the USA. We are allowed to own the semi-auto version of the AK-47, M16, G3, etc. but not full the auto versions. And, contrary to what many may think, they function no differently than the old Remington Model 8 semi-auto hunting rifle that's been around since shortly after the turn of the last century. They look a little different but their function is the same, magazine fed and one shot with each pull of the trigger.
Some would classify the M14 and M16 semi-auto version as an assault weapon, but they are not. So what use would anyone have for either? Well they happen to be the two consistent winners in the very popular target rifle shooting sport here known as NRA High-Power Competition. In fact our USA National High-power Target Championships are just finishing up at Camp Perry Ohio. And if you were there, you'd see hundreds of them in use in three position paper target shooting, targets no different than those used in the UK Full-Bore matches.
Also, the states here in the USA with the highest crime rates are those with the strictest firearms laws, so Roman's analogy isn't quite correct. And I notice that violent and firearms crime in the UK and Australia have heavily increased since their (near outright) firearms bans have been in place in both countries.
I live in the state of Idaho, a state with very few firearms laws, and lots of firearm owners. We also have the right to carry firearms concealed (after applying for a permit), yet we have one of the lowest crime rates in the USA.
As has been said, "An armed society is a polite society."
My 2 cents worth from this side of the pond.
Regards,
Don