Very interesting. I will research these cases. What is your theory as to why the NRA is hush about them? I’m don’t know why the NRA stays clear of the NFA. The NFA is the root of all gun control.
I think it goes way back. The NRA has been around for a long time. It hasn't been until relatively modern times that they've really taken point on a lot of the legal side of things. The NRA still, to this day spends more on education and 'hunter' issues than they do actually combating legislation or backing challenges to gun control acts in court. To the best of my knowledge, according to the research I've seen, the NRA did not oppose the 1934 or 1968 'gun control' acts. They weren't behind Heller when it first came up. You'd never know that from media accounts, but it's true nonetheless.
IMO, they are cowards who aren't really completely comfortable with the full meaning of the 2nd Amendment. They have never really ever disputed (that I've seen anyway) the complete misreading of the Miller decision that you see in most commentary about it.
Here's a direct quote from U.S. v. Miller
"In the absence of any evidence tending to show that possession or use of a "shotgun having a barrel of less than eighteen inches in length" at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia, we cannot say that the Second Amendment guarantees the right to keep and bear such an instrument. Certainly it is not within judicial notice that this weapon is any part of the ordinary military equipment or that its use could contribute to the common defense. Aymette v. State, 2 Humphreys (Tenn.) 154, 158."
In other words, the government lied to the court to its face and said sawed off shotguns were not used by the military. Sawed off shotguns played an important part in the trench warefare of WWI just a few years prior. So, what the court essentially said was that if they'd been shown that a sawed off shotgun were a military weapon, it would have been covered under the Second Amendment. (The case had nothing at all to do with full-auto weapons, so they weren't considered for the purposes of the ruling).
The excellent book "Unintended Consequences" covers the Miller case rather well, and accurately IMO.
The above Miller link on my website has more information about the case than you'll find pretty much anywhere.
The Dalton and Rock Island Armory cases are interesting IMO, as I've found references online where the cases were cited as a positive defense, but the judges involved twisted themselves into pretzels to claim that the binding precedent did not apply in the cases at hand.
As to why the NRA (and other orgs I could name) haven't made a bigger deal of these opinion (which are still good precedent as far as I can tell), I can't really say, other than to comment on the weak-kneed nature of the NRA. They don't care about NFA weapons at all it seems. I'd like to see the NFA struck if for no other reason than that it would remove the incredibly stupid regulations on suppressors. To me, that is a safety issue that should have been removed via legislation years ago.