We also see statistics quoted saying that the number of firearms is higher than that of other developed countries.
I'd like to see statistics comparing the number of murders with other weapons. It is perfectly plausible that we have an elevated rate of gun ownership for historical or cultural reasons, and (since they are such highly engineered weapons) we tend to use guns to murder people, rather than other weapons.
If number of murders perpetrated with other weapons is lower than in other countries, its entirely possible that enforcing stricter gun control would not have a significant effect on the total number of murders.
Factors that might go against this hypothesis are the fact that gun availability might encourage people to kill more readily, gun availability makes a successful murder easier, etc... There are a host of other confounding factors, as well.
I don't really have strong a priori beliefs about these questions, but I'd like to see some more statistics. Another interesting statistic would be to see a time-series comparison of overall homicides, gun homicides and gun ownership in America over time.