Well, there are also 12 gauge shotguns that have a rifled barrel, but never mind.
I think thats what I said by

Even a shotgun is not classed a rifle.

What I want to point out is, that the term "rifle" makes the stats insignificant. Of course not so many criminal run around with a rifle, while every idiot can buy a hammer and hide it under the clothes. I bet even a lot more murders are carried out with a knife than with rifles and hammers combined.
Its not the question if a statistic is true or not, its more about how its designed to present a certain scenario.

To the suicides... It is true that someone who is determined to kill himself will find a way to do so, or at least try.
However, the death wish is often a reaction out of desperation in a certain situation. A lot of times "sleeping over it" might change the view of that person again. A gun in easy reach however can cause the person to carry out the suicide too quickly, before having a chance for second thoughts.