Link

Does this apply to full-auto firearms?

Will the law stick in all circumstances?

Give it a go and report back on your findings. I fear the Feds have already made it clear on this type of thing and it's not positive.

I believe myob is the focus for this one.  Those who abide by it do so without posting or making fanfare.  More than one homemade suppressor has been put to use after this went into law.  
As for full-auto.  Well, no one wants to be the first one through the door.

No full auto - Subsection 4 (d) regarding what it doesn't apply to....

"(d)  A firearm that discharges two (2) or more rounds of ammunition with one (1) activation of the trigger or other firing device."

Also doesn't apply to anything one person can't carry alone, exploding ammo etc...

Kansas has a similar law and these two guys were convicted.  And they lost their appeal.
Ruling: Kansas gun law no defense to federal firearm charges

As mentioned above it becomes a case of discretion is your friend. Didn't Montana and the Feds fight on this pretty early after they passed something similar?

It's the same as the legal marijuana in states.  The feds can bust you if they want.  Our law enforcement and DAs are not supposed to.

Hasn't that already been done in California to ICE?

Yes, and Montana lost at SCOTUS a decade ago. Kansas lost at SCOTUS too.

If you rely on this law, maybe you can use it to wipe your ass in prison. It’s a lazy way for politicians to say they did something for gun owners when they really did nothing.

IMHO, you cannot rely on the concept of law any more...period.
Our judicial system is utterly FUBAR'd beyond the point of no return and the courts are completely useless and believing otherwise is obsolete thinking at this point.
All we really have to rely on is the human terrain and the political terrain within which we live and whether or not that works for us or against us.
Hence why I moved to Idaho.
As a Christian Conservative church-going person, I know that the human and political terrain in Washington State is working against me and all that I believe and hold dear.
As long as I stay there, I am nothing but a hated tax-cow for the Leftist radicals. They want to tax me to death to support their leftist agenda, but they hate my guts and want to persecute me and my family and brow-beat us into utter submission.
Life is simply too short and precious to continue  living in such a place.
So that is why I am here...not to speculate on the housing market, but to simply live in a free state.
If I am going to continue to pay my taxes, tithe to my local church, contribute to my local food bank, and contribute to my community, then I will do so within a community with some semblance of decency and traditional values and recognizes the rights of free and sovereign people and the freedom to worship my Creator and my Lord and Savior.

Amen ARctangent. It’s hard to believe how bad WA is these days. I feel a sigh of relief every time I hit the border.

Well they did it with the marijuana laws and the feds finally backed off. Maybe if a majority of states do this the feds will do the same.

Wouldn't that be pretty hard to do? Build a homemade suppressor out of what? A mag light tube from where ever they're made, or chinese tail pipe tubing.
80% lower is imported,then your barrel, upper, bolt and carrier... All most likely from somewhere else.

The US Federal Government only requires 50% of any product be manufactured domestically to qualify as a "Made in USA" product.
If the Feds can enact such a regulation, then I don't see why Idahoans can't.
Fair is fair.
Either a law applies fairly and equally to everyone or it isn't a law IMHO.

That's a fine thought, just don't expect the government to actually act fairly or play by the rules.

Lol...no, I dont.
The Constitution and Bill of Rights, the rule of law, the Judiciary, rules of common decency and morality, it's all gone at this point.
The United States as a nation/republic officially failed on November 3rd, 2020.
It's only a matter of time before everything descends into hell and chaos at this point.
Honestly...I am just a harmless nobody.
They've got far bigger things to worry about.