I continue to extoll the virtues of this platform as your basic home defense firearm. You will never regret having one of these, find many people who it fits perfectly and know it could serve anybody well as an only home defense weapon if you have limited choices.
It has not been long since I published 20 gauge youth pump as #1 home defense weapon choice (April 26th), but I did not include a link to the one I would be purchasing were I in the market today:
Mossberg 500 Tactical 8 Shot Pump Shotgun
I would simply go to a local dealer, even if it cost a few bucks more, shopping local is always a good idea when their prices are within reason, service is good and selection is adequate.
Why do I keep singing the praises of the 20 gauge? … and why the shorter stock?

8 gauge shotgun
An intelligent man watching his wife at 60% of his muscle, meat and bone shoulder, hold and fire my lovely, heavy, full-sized ‘Marine Corps’ Mossberg 590A Special Purpose 12-gauge would find it disproportionate. In simpler terms, “This ain’t right”.
Simply holding it up is far more effort for her than he. Then the 12 gauge recoil kicks in. Mister 200-pound tough guy is moved slightly by it. If he is fortunate enough to have a cute 120-pound mate, it rocks her world. Idiots and those of frail egos are amused. Intelligent men see lack of balance.
For proportion Mr Weak Ego should track down an 8-gauge shotgun and fire off a dozen rounds. He might be getting the point somewhere along the way.
IF you want your slighter-built mate to be part of your household defense system, acquire a shotgun you both can use. A 20-gauge youth-stocked pump shotgun with a generous magazine tube is about as good as it gets.
For commparison sake, check out the shotgun energy chart here:
https://www.thefixer.biz/2013/03/03/shotgun-muzzle-energy/
The mighty 12-gauge is not blowing away the 20. Suffice it to say, “Twenty is plenty.”
Manufacturers are FINALLY getting it. Therefore, we can get them. For the guys, shooting a bunch of targets is easy and fun. Pretty much the same for the gals. Velocity and payload are way more than adequate for self defense, home defense, hunting and clay pigeons.
I’ll point out that women generally are smaller than men and the youth stock puts the long gun in a similar position as adult male stocks put full sized guns on full sized men. How can that bit of common sense be new? … but it seems to be relatively so.
THE gun readily accessed by her should be this 20 gauge. If you have two, go ahead and set your 12 gauge by its side…
or a second 20 gauge with the adult male sized stock…
then put in a supply of 20 gauge birdshot, buckshot and slugs to share.
Here is a video covering much of that turf.
Why a 20 gauge? Youth model???
There is no RIGHT ANSWER.
But there are some poor choices often made.
The Mossberg below is not among them.

Mossberg 500 Tactical Pump Action Shotgun 20 Gauge 20″ Barrel 3″ Chamber 7 Rounds Ghost Ring Fiber Optic Front Sight Bantam 13″ Length of Pull Synthetic Stock Matte Blued Finish
As I mentioned and linked to above the 20 gauge delivers a slightly smaller load than the 12 with both having similar velocity. That is to say, each pellet hits with the same force the only difference being the number of pellets (not a big difference) and the recoil (A BIG DIFFERENCE).
Other shotguns in regular use are the 28 gauge and .410. The four-ten is primarily an expert’s gun – more expensive to buy, with more expensive ammo, and a much smaller payload. Shotgunners who easily hit everything they shoot at with a 12 or 20 gauge sometimes buy a nice four-ten for the challenge and bragging rights earned by taking targets and game with a small fraction of the payload compared to a 20 or 12 gauge.
Similar in recoil to the .410 and even more expensive to feed is the 28 gauge. A slightly larger payload with similar velocity to the other shotguns mentioned its main attraction is in a lightweight single-shot for expert upland game hunters who want the quicker action compared to the heavier guns and a few more pellets over the four-ten.
You might notice I label both smaller bores as “expert’s guns”. Thus we have 12 gauge for big recoil-insensitive people, 20 gauge for everybody else and choices between 12, 20, 28, .410 and even more obscure others for the experts with a particular itch to scratch.
Start with a 20. If you ever want another shotgun, you will know what it should be and why.