Here...Canada is actually really high up there in gun ownership. As far as I know, it's mostly shotguns and rifles, but some of those rifles would be considered "assault weapons" per the definitions tossed around here. The fact is, "rifles" in most populations usually aren't used as much in crime, even if they are more easily available. I'd imagine it's because it's a lot easier to be caught with it. Which is why 90% of all gun crime in the U.S. is done with handguns. (Which is why most people roll their eyes when people talk about banning "assault weapons", because they are literally the least used type of gun in gun crimes.)
Canada's crime rate is lower due to a number of factors. I'd say the biggest though is simply your poverty rate.
An example in the U.S. would be Chicago and New York. Chicago has a horrible murder rate, New York has a very low one (Historic lows last year...even by comparison world wide it's low)...Both have absolutely draconian gun laws. So what's the difference? Check out the property values in most of New York. Compare it with crime rates.
Wealth and access to services does more to limit homicides than any law will. Which is why it's silly to spend political capital on this, when we don't even have real healthcare yet.