Kent... to try to address the basics of your points:


1. ..."There never has been, and likely never will be, a randomized trial of gun control."
   Indeed... it is hard to do a double-blind test of many issues like this. You cannot have everyone turn in their guns for 3 years and 'see' what happens to the violent crime rate....then give them back if we don't see progress. (I happen to think there WOULD be progress, but it is obviously an unworkable idea, as the criminals, the paranoid and the unstable would simply not cooperate.)
   All we can/could possibly do is to reduce future expansion of the number of illegal guns, WHILE expanding the categories of what is illegal.,,,(including types of ammunition).


2......."both according to a natural language reading the Bill of Rights, and according to the U.S. Supreme Court throughout history".
Well, here I obviously disagree with the 1st part, as I still think that changes in society show that the language of the 2nd amendment has de facto become ambiguous as the concept of 'militia' had changed. The founders simply had no way of knowing what would be invented.
But the 2nd part...sure..the courts have continued to 'interpret' the 2nd amendment as if there was no ambiguity, So? It seems to me this is about 87.4569% a political stance. Judges get appointed & confirmed based on their commitment to certain aspects of the status quo.. This bothers me on several issues, not just gun control.....but it is a fact, and I am trying to make my suggestions with that situation in mind.

"What happens today to the Second Amendment can happen tomorrow to the First"
I simply reject that as a way of deciding what is right to do! With a little bit of Gerrymandered thinking, that notion can be used to reject ANY law that seems to limit anyone's freedom to do ANYTHING. (As I said above, it is an example of the "slippery slope" fallacy of reasoning.) Each amendment must be treated on its own merits, and there is little about the 1st amendment that either represents a danger, or that any sizable portion of the public disagrees with. You 'might' someday, if the winds blow differently, get 2/3 of the states to ratify a change in the 2nd amendment, but hardly the 1st. (no, I won't hold my breath)

3..........
"If you want to reduce a crime, any crime, put more policeman on the streets, increase their training, improve the crime labs, and tighten sentencing, probation, and parole rules. More consistency in enforcing the laws ALREADY ON THE BOOKS for lesser offenses will also likely reduce the incidence of more serious crimes. For example, consistent enforcement of existing law against a wife-beater will likely reduce the chance that he will become a wife-killer."

Sure...nice principles..... Ask the policemen already on the streets how many more they need. How many more do YOU think we need?...and where will you find decent, qualified police? Volume does little good if you can't trust them. And if you hypothesize that it is possible, how will you pay them? And IF you get that far, and they (and the courts) do a good job of enforcement, where will you put those convicted? I read about terrible overcrowding of prisons now! Gun violators will be competing for space with drug dealers, gang members and all those wife beaters..(yes, I know they are often the same, but it is STILL a serious increase in the need for jails & prisons, and the trend is away from the death penalty.)
I'm sorry, but my claim is - that the existing laws are poorly designed, largely because the NRA spends millions to keep them watered down, and just a few individual states, (like Virginia, mentioned above), can make efforts in other states almost useless. That, coupled with all the existing weapons hidden away, both 'legally' and illegally, make the very idea of "enforcing the laws ALREADY ON THE BOOKS" a frustration to those overworked police, and a **JOKE** to both criminals and just macho fools who think they can 'settle their own scores'...thereby becoming criminals.

What *I* assert is needed are changes that will
1) Stop the proliferation of NEW guns into an already saturated market.
2) Gradually reduce the totals of guns that the police...(both the overworked one we have, and the ones YOU are gonna hire & train).. agree are totally inappropriate for "Mr. Average Citizen"
3) Restrict the sale of 'heavy duty' ammunition...seriously!
4) Do ALL the education, social engineering, counseling that we as a society can manage to keep people from the IDEA of violence as a solution
and
5)...oh, yeah...TRY to enforce the laws ON the books better while we are trying to GET the money for more police and write some laws they can use...(that are not being made irrelevant by the state just across the river.) I live in the Maryland suburbs of Wash. DC....I see all these conflicts and their outcomes on my newscasts every day.