Phillip 1882...
Machine Guns Illegal? Why?
This shows that you haven't read and understood Colonel Jeff Cooper.
Technically "Machine Gun" means a belt fed, crew served, tripod mounted weapon in a full-powered rifle cartridge.
As The Good Colonel said over and over again, a "Machine Pistol"—as he used the term, any carbine in a pistol caliber—is heavier, bulkier, burns beaucoup more ammunition and makes a good deal of racket...
But is no more effective than a Pistol in the same caliber.
"Eighteen rounds of .45 in the torso from a Thompson won't make him any deader than two rounds from 1911a1 and actually take longer to deliver."
Cooper also said, "Hand-Held Auto-Fire is generally a drag."
By which he meant relatively ineffective.
People who "Spray" find that even with many foes there is much more empty air that sprayed rounds can disappear into without effect than enemy torsos that can be randomly hit.
But that presupposes that people shouldn't be allowed really awesome weapons—I don't agree so arguments about efficacy are pointless.
I will say that men live via their Weapons and outlawing things like Sawed-Off Shotguns, Automatic Weapons, Switchblade Knives, etc.—Warps and Distorts a man's Psyche as much as the old Chinese Foot-Binding Warped Women's feet.
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Utopia?
If I had one wish to ask the magic Genie—I'd wish that all restrictions on Weapons were permanently removed and the very concept could no longer Exist in the Human mind.
{That would prevent a subsequent wisher from unwishing my wish...}
And I'd be selling plasma to save up enough money for a Czech Skorpion and a Roadwarrior 12 Gauge.
{Disabled me—like about $950/month net...}
But aside from that:
As Robert Ringer once observed (paraphrased)...
"One Dude's idea of 'Peace' is to enjoy his 10 000 Acre ranch without let or hindrance while another Dude's idea of 'Peace' is to forcibly appropriate the first Dude's 10 000 Acre ranch, cut it up into 100 Acre Plots and distribute the parcels to those he feels are worthy.
"As long as people have such disparate ideas as to what constitutes 'Peace' lack of hostility is highly unlikely."
I assume that "Peace" is a requisite to "Utopia'.
Since Utopia is a Phantasy anyway—a true Utopia would have a never-ending Frontier where Recalcitrant folk could load up and move to and do things their own way.
"Space" certainly doesn't fit the bill. It is almost certain that emigration to Space will never make even the most minor inroad into the Earth's population and the folks selected will almost certainly be buttoned-down, professional, obedient and have what Tom Wolfe called, "The Right Stuff".
I had an idea for a SF/Phantasy story that I may write one day...
But in our near future "Alternate Universes" {Which in this sense are almost certainly a Phantasy—or at most an Urban Legend—but never mind—the concept is well defined in Fiction...} are discovered—the vast majority largely images of our Earth say 1000 or 2000 years ago—same continents, flora and fauna, even generally having mineral deposits in the same place...
But 999 out of every 1000 without man.
And moving from one World to the other turns out to be dirt cheap.
It would kinda be like Cyberpunk meets "Silverado"—there would be many modern devices—particularly hand held ones—but a lot of the day to day life would be almost Amish or old West...
And the Frontier never ends.
Mankind continues to expand geometrically into an infinite number of parallel worlds forever.
But imagine Recalcitrant and Trucelent folk who are always on the cutting edge of the advancing horde and their ancestors have also been in the vanguard for thousands of years.
That would be a UTOPIA!
Saxon Violence