You had me convinced at one time that this was an issue. Now I know it is not a significant factor impeding the control of ownership of certain types of dangerous weapons because the distribution of these particular weapons is far from uniform.
Well, were I President, I would first strongly advocate for the adoption of Canada's gun laws, word for word (leaving out any reference to the Queen, of course.

) Canada's gun laws are very friendly toward sportsmen. I would then advocate legislation that would create a long transition period with just compensation for anyone owning guns that would not be allowed under the new law. (In Canada pistols with short barrels are not available and I believe semi-automatics must be registered with the government -- those types that are allowed. Some types of otherwise banned weapons can be owned with special licensing, if sufficient justification can be shown.) After the transition period, I would advocate for adoption of the same penalties Canada imposes on those in violation of their gun laws.