Has anyone ever tried to mount a 2nd Amendment defense for explosives possession?

So did Hitler’s Germany.

Except for the Jews.

The Jews were a very small fraction of the German population. The non-Jews had lots of guns until the occupying Allies disarmed them.

And how did that work out for the Jews?

Even if the Jews had not been disarmed, the end result would not have changed significantly. They were vastly outnumbered and not organized for resistance to being rounded up.

Did you actually read your own cite? Because the Nazis loosened gun ownership laws at the same time that they forbade their ownership by Jews - among a host of other things Jews were no longer allowed to do or own. Note in particular the bolded part which states which groups no longer needed permits to own firearms, and which groups were prohibited from owning any weapons.

In 1938, the Nazi Party reformed weapons law thoroughly. Today, the Waffengesetz of 18 March 1938 (RGBl I, 265) is sometimes seen as a relaxation of existing regulations, even though it solely benefited privileged members of the NSDAP and its associated organizations.[4] The law stated that certain groups of NSDAP officials did not need any permit anymore for weapons possession. Amongst them were Unterführer of the NSDAP, starting from Ortsgruppenleiter, the Sturmabteilung, the Schutzstaffel, the National Socialist Motor Corps and also the Hitler youth, starting at Bannführer. The new weapons law also prohibited the possession of any weapons to certain groups of people, namely Gypsies and all individuals who lost their “Civil Honors” or who were under supervision of the police. The latter also included people convicted due to homosexuality.

Directly after the Kristallnacht, the possession of any weapons by Jews was prohibited through the Verordnung gegen den Waffenbesitz der Juden, enacted on 11 November 1938 (RGBl. I, 1573).

A contemporary report of the apostolic nuntius of Berlin to Eugenio Pacelli about the Kristallnacht stated: „Also, all weapons were taken from the Jews; and even though the purpose of that was altogether different, it was good, because the ideation of suicide must have been enormous in some.“[5]

You also know that Kristallnacht was orchestrated by the Sturmabteilung and Schutzstaffel - the SA and SS who no longer needed permits to own firearms - in ‘retaliation’ for the assassination of a German diplomat with a pistol at the hands of a German-born Polish Jew in Paris, right?

Yeah, if I own an AR-15 and want to go out to a farm and shoot cans with it, that’s most definately a “lawful purpose” but wouldn’t appear in any law enforcement databases. Even taking it to a private rifle range wouldn’t.

I don’t own an AR-15 but I do own several other semi-automatic rifles- M1 Carbine, M1 Garand, original Soviet issue SKS-45, and do take them target shooting along with my bolt-action stuff.

Trying not to get too far off topic - one major reason for the holocaust tragedy was that Jews had been subjected to assorted mistreatment by authorities over the years. Various governments often rounded them up and relocated them, forbade them certain professions or commerce with non-Jews, confiscated property under various pretexts, etc. Local citizens often rioted and attacked Jews, beating, killing, destroying property. Whether armed or not, resistance would simply provoke response - further government action if they resisted authorities, and retaliation by government taking the side of the gentiles if they injured any trying to defend themselves. So, they passively allowed themselves to be gradually more restrcted under the hope that “this too shall pass”, and a lack or awareness of the horror growing around them.

So having any firearms would not have done any good. The scenario is not different than what happened with American natives, or in Tulsa 1922 - any resistance provokes a much stronger response, and the authorites will only fight for one side no matter who is truly at fault.

Considering the most common gun in American households is a 12 gauge shotgun and having (unfortunately) seen photos of what a 12 gauge round can do to a person’s head, I kind of doubt a 5.56mm bullet somehow can top that.

TBH, I don’t remember what I meant, but I think it was "could you make the case that my pipe bomb/hand grenade/mortar round/etc. is legal under the 2nd Amendment? As far as CBRN weapons are concerned, I think that while idiots can argue that the 2nd Amendment allows their possession, the real answer is Fuck Around and Find Out. If you somehow possessed a nuclear weapon as a civilian, the government would probably deploy CAG or the nearest F16 and no one left alive would have standing to bring a 2A challenge.