I know this isn’t the best place to ask this, but I’ve learned that asking hobbyists for their opinion usually isn’t a good idea because they basically say unless you’re buying the most expensive item available, you’re wasting your time. And a lot of the time that isn’t true.
I’ve read the JTS M12AK isn’t bad, but there are multiple models under $500. Keep in mind this wouldn’t be the primary gun for home defense, just something fun to shoot occasionally at the range.
It sure looks fun. And I would not hesitate using it for home defense as just on looks alone its badass.
Yeah, it looks fun but I’d worry about jamming in a home defense situation. I would rather have a reliable 9mm as the primary home defense weapon.
FWIW, there are multiple models of semi auto, magazine fed 12 gauge shotguns under $500 out there (many times under $300 if you shop around).
JTS M12AK
UTAS XTR-12
Panzer Arms BP12 (this one has a bullpup design)
G-Force AR-12
Escort SDX 12
The list of manufacturers and designs goes on.
By “magazine fed” you seem to be meaning a detachable “box” magazine?
Tube fed semi-autos have proven themselves to be very reliable over decades and decades. One with a 20" barrel could be a good choice.
The box mag ones are somewhat newer, and seem to be aimed at the AR15/AK47 crowd. The one you mention is quite heavy. I would veer away from any military looking gun, due to possible gun control bans.
When I was working at the sporting goods store, we sold a lot of Double barreled side by side coach shotguns. They came highly recommended by the cop customers for home defense. Foolproof and lightweight. Looks really badass. About as ban-proof as can be.
The other gun suggested was a 4" barrel .38 revolver. Also foolproof, no worry about jams or safeties.
(as far as any deadly weapon can be “foolproof” of course)
Yep, I agree. But others suggested a revolver. YMMV of course.
I’m going to reluctantly agree with @DrDeth (not that he said anything wrong) in that tactikool weapons are the ones most likely to be targeted by legislation, rather than functionality.
Having said that, it depends on the sort of fun you want to have and your budget. You’re absolutely correct, you don’t have to spend a ton of money on a firearm to have a fun, reliable weapon. But, if I was looking to shoot something at the range, I’d be looking for something cheaper to shoot - .22, 9mm, or maybe 5.56, although nothing is ‘cheap’ these days.
If I was wanting a 12g specifically, and didn’t want to draw eyes, I’d get a Remington 870 12g Pump with wood furniture, new or gently used, which should last fundamentally forever. Should still be under $500 depending where you shop.
The other reason I tend to look sideways at some semi-autos, is that if magazine bans / size bans get put into place it can get hard and expensive to replace or get compliant options.
I have one of the AK magazine fed shotguns. 10 round detachable magazine. Don’t shoot it much, but it’s a lot of fun when we do so.
Took it to a sporting clays course once and we shot it on the Rabbit stage. Told the trap guy to fire them out as fast as he could. I didn’t hit them all, but it was great. Then the other four guys had to have a go.
Semi-auto shotguns? Those are for amateurs and wannabees. I want an AA-12. 
So yea, a semi-auto shotgun is a hoot to shoot on the range. And perhaps my reasoning is all wrong, but would I think a semi-auto shotgun would best for home defense. Mainly because you only need to squeeze the trigger; you won’t have to remember to work the forestock. (And yes, I know racking the forestock should be burned into muscle memory through lots of training. But not everyone can can devote a lot of time to training. And even with lots of training, stress & tunnel vision during a self-defense situation will make you forget to do simple things.)
For hunting I recommend a Mossberg 500 or Remington 870 pump shotgun. They’re cheap and reliable, and there are a zillion accessories you can buy for them. And because they’re cheap, you won’t care if it gets dirty or scratched. I recommend a synthetic stock & forestock over wood.
Let me just say I’m glad I’m not that guys neighbor. (not directed at OP at all)
I wouldn’t say ‘cheap’, I’d say good value for money for those two models, and yes, I should have included the Mossberg as well as the Remington in my list, but Remington is what I have and it’s my first thought.
I recommended wood over synthetic to cut down on the security / gun control theater that often happens, rather than absolute practicality, but I am still a fan of wood features on my firearms for aesthetic reasons.
As for hone defense scenarios, the OP specified that it wouldn’t be a primary home-defense weapon, so I left that factor out of my evaluations. For those scenarios, I want something that’s easy to get in and out of a secure personal safe, so I normally go with handguns. A shotgun almost certainly a better option in most scenarios, but harder to secure in the bedroom to my satisfaction. But that’s another thread!
An excellent choice. Shorter barrel, tho. 20"?
Barrel length depending on what the OP wants of course. 20" is a good compromise for a range gun that might be a backup home defense weapon. I certainly see it as a fine, multipurpose option.
True. A bit longer for some uses, of course. Re-reading the OP, and seeing that it will not be the primary home defense weapon, I withdraw the coach gun for the OP.
Still a double-barrel is not a bad option.
My best selling long gun right now is the Rock Island VR60. It’s a semi-auto shotgun in an AR15 configuration. It retails for $389.
It comes with 3 five round mags but 9 and 19 round magazines are available after market. It’s 12 gauge and will accept 3 inch magnums.
I own one myself of course and it is an absolute blast to shoot. When I’m at the range or in the woods shooting people beg me to let them try it.
Except about 30 years ago there was talk about incorporating double barrels into the assault weapons ban because it’s possible to fire 2 rounds at once.
Don’t put anything past the antis.
I own a magazine fed AR-15 style shotgun and I have to say when it jams it JAMS. Its all mainly magazine feeding issues but I wouldn’t trust it as anything but a range toy were I have plenty of time to drop and reinsert the magazine.
When you’re in the woods shooting people with another gun, do they not beg you then as well?
(Punctuation: it saves lives)
He is playing a character. The Russian accent is fake. He’s an American named Kyle Myers. He had one of the early successful gun channels on youtube.
He ran into legal issues, and one of his friends ended up getting shot to death. That case is still unsolved (and there are lots of conspiracy theories going around about it). He also served time in jail for drug possession (if I recall correctly) which I think is what killed his channel. Illegal drug users aren’t allowed to possess firearms.
So yeah you probably don’t want to be the guy’s neighbor, but probably not for the reasons you think. 
What make?
And are the magazines aftermarket?
Keep new magazines stored fully loaded. This helps with feeding issues.
Some aftermarket mags are fine like Mec Gar and Shield. Stay away from Pro Mag which is an acronym for Please Remember Our Magazines Are Garbage. I refuse to sell them.
They don’t make them anymore but if you come across one stay away from Ram Line. They used a coil rather than a spring and their mags were crap.
This is interesting. I would have thought that keeping the springs tight like that could weaken them (my assumption is that there’s a spring mechanism that keeps the pressure on the shells?).
This is a silly argument. Every U.S. “gun ban” to date has been a prohibition on the sale or transfer of guns, and usually just new guns. The assault weapons ban led to a massive increase in the value of “pre-ban” guns. If sales of new box-fed magazine semi-auto shotguns are banned, the value of used ones will go through the roof because morons - excuse me, “gun enthusiasts” - will slaver over them. Your advice seems to be “Make sure you don’t buy any cheap guns that will almost surely increase in value!” I hope you invest better than that.
If there a real take-them-from-your-cold-dead-hands ban (not that there will be), owners would compensated the fair value of their guns because the Fifth Amendment prohibits seizure of property without just compensation. (Note to gun owners - there are entire parts of the Bill of Rights that don’t mention arms at all!)
Talk from whom? Anyone other than NRA fearmongers trying to rile up gun owners? This is FQ. Cite please.