Pry your gun from your cold dead fingers? Nah, we'll just beanbag you while the flash-bangs are going off
That, sadly, is idiocy. You and your AR-15 will not stand a chance even against the sheriff's shitkicker SWAT team if they know what they're doing: they can come at you without you getting a shot off - they can do robots, explosive entry, smoke, CS and/or flash-crash grenades, and because you're armed they might be twitchy enough to shoot you with proper bullets instead of beanbags - but probably not. Even if you hit some of them before you go down they probably have rifle-proof body armour nowadays.
They probably won't storm your house right away, but that's not because they're afraid. The thing that's slowing them down isn't your AR-15, it's their desire to avoid killing or hurting you.
Supposing you're a real hardcase and you manage to piss them off, the federal oppressors might let the real big dogs off the leash. You and your militia buddies won't last long against a "rifle" company of paratroopers with their rocket launchers, machine guns, frags and the rest - and rifle companies are pretty much the gentlest thing the US combat forces have. (And please, oh please, don't start burbling on about the Posse Comitatus act and say that US troops can't be used to enforce the federal government's will on US soil: tell that to the ghost of one-time Arkansas governor Orval Faubus. He was presumably quite upset when President Eisenhower sent the 101st Airborne to ensure that black kids could attend the Central High School in Little Rock.)
So. AR-15s don't keep you safe from government oppression: you'd need everything up to stealth fighters and nuclear weapons for that. It's not clear whether the drafters of the Second Amendment wanted to emphasise "well regulated" and "security" or the bit about the right to keep and bear arms not being infringed, but the realities of force have changed an awful lot since 1791. Small arms are no longer any guarantee of freedom, if they ever were.
So Wilson and his pals are frankly being at least as unrealistic as the gun-control mob. Guns don't keep you free: ironically perhaps, for those like Wilson who seem to believe that freedom is best achieved by circumventing laws (albeit laws that don't actually exist), it is laws that keep you free. It's the law that means you can have a gun no matter what the feds want, and no matter that they could easily take it away if they wanted/were allowed to.
If the US decided to have laws against guns rather than against full-auto weapons, crap like the Ghost Gunner wouldn't save you. It is not the receiver that's difficult to make, it's the barrel, and to make a gun barrel you need a lot of specialist kit which isn't used for anything much else.
It's laws and, dammit, governments which keep you free - not guns. After all, a sensible American would hardly say to himself, well, I won't travel to or work in Britain because they have strict gun control there and so I won't enjoy basic freedoms - it would be silly. Honest: we have habeas corpus and trial by jury and freedom of association, all the good stuff. We pay very similar amounts of tax, whether we're rich or poor. And it's probably a bit harder for our government to physically oppress us, as nearly all the police, feds**** etc are unarmed too!
So: as you were. Nothing to see here. Move along. ®
*Depending on what calibre you choose: full-fat high powered rounds such as 7.62mm NATO would technically be a battle rifle, intermediate-power stuff such as 5.56mm NATO would be an assault rifle.
**Though that would be illegal unless you have a manufacturer's licence and have paid the associated occupational tax up date ($1000 or sometimes $500 pa). If you have done all that red tape you're good, but you mustn't sell the resulting full auto weapon/receiver to anyone except the cops or the military. Private citizens who are not licenced manufacturers can own full-auto weapons in the States, but only guns made or imported before 1986. Such weapons, being in limited supply and high demand, cost a lot of money.
***It's very troublesome to legally own a firearm of any kind in the UK and all such private weapons are subject to intensive registration, licencing and regulations. There is almost no opportunity at all for a private citizen to own anything other than a shotgun or a bolt-action rifle for hunting or target use, though the legal definitions of "shotgun" and "rifle" can be stretched to cover some very interesting items - such as the VZ-58 MARS action rifle, which gets around the UK's ban on semi-automatic rifles through a novel trigger-operated system.
****The UK spends more of its GDP on policing than the US does and we are heavily policed, with around 140,000 officers in recent times. But only a few per cent are authorised to carry weapons, and many even among these aren't available for oppression as they aren't on armed duties or are employed on security-guard type tasks etc (the largest armed police command in the UK is the Metropolitan Police Diplomatic Protection Group, with 700 officers who are mainly employed guarding embassies). There isn't really any equivalent of America's BATF, FBI, DEA and other large, armed central law-enforcement bureaux. The police officers and other government personnel (MI5 etc) who do those jobs are almost never armed.
Your correspondent is unlike most journalists - and most Brits - in that he has some liking for, experience with and knowledge of guns and other weaponry. My death-tech CV can be read at the bottom of this article by those interested.