True, except that most of the States that have strict gun laws also have and have had some of the lowest gun ownership per their population, so correlating strict gun laws with a reduction is crime is not as clear cut as it may seem. I would also bring up the fact that most violent crimes that involved a firearm were committed by criminals that had no legal right to own the firearm they used, hence the laws really only impact those that legally obtain their firearms.
Correct on registration, as Canada has had it for years and they have not shown any real use for it, well except for now, since they passed their Bans they now know exactly who legally owns firearms and what kinds, meaning they know who has what and who needs to turn them in or face legal issues.
So what it comes down to is that bans are really no more than feel-good laws that in reality would not impact crime in any significant way, and registration really serves no other purpose than to use the information to take away firearms. The bigger problem is bans and registration would actually turn Millions of Americans into criminals, because few would be willing to turn in their firearms and most would not register those firearms and as a result any such effort would be a failure.
Maybe instead of focusing on Firearms we focus on the causes of violent shooting, criminals and the mentally ill, or would that be too hard?