"assault weapon" is a pejorative term used by gun grabbers and anti liberty types frequently but none of them are able to define it consistently.  Do you know that the 1994 Assault Weapons Ban defined which weapons were "assault rifles" by having Dianne Feinstein sit down with a picture book full of rifles and picking which ones she thought were "assault rifles"?
In many cases the same gun with wood stocks is not an assault rifle as when it has plastic stocks! Does the material the stocks are made from make it more deadly?
No one has any actual figures on "assault rifles" because it's a made up and vague term but the FBI does classify "rifles" as a separate category that includes all rifles including ones with scary plastic stocks. 

Rifles of all types are used in fewer homicides than hands and feet or blunt objects.  Hands and feet are more deadly than "assault rifles" because they are so rarely used in crimes.  So if all rifles disappeared overnight it wouldn't significantly reduce the number of homicides, in fact it wouldn't reduce them at all, wouldn't the people who used rifles just use pistols instead like some of the most successful mass shooters have done?
In fact rifles enhance safety in neighborhoods and towns. In addition to being essential tools for pest control and hunting. 
So if we ban them there is zero benefit but many harms. 

In America we had an assault weapons ban for a decade, it utterly failed to achieve any of it's goals. 
Isn't the definition of insanity doing the same things over and expecting different results? Maybe Joe just forgot we already tried it and it failed?
You know what they did achieve?  The ban caused Americans to run out and buy millions and millions of AR-15s, several times as many as had been previously sold in the weapons 40 year history at the time.