H&R made about Bazillion of those almost forever and yep they are legal. (Silver Creek Slim posted the SASS Handbook SHOTGUN REQUIREMENTS...)
Sears and Wool-co and just about every hardware store in between sold them.
It was still common in the early 70's to see them, in K mart, probable till H&R shut it's doors.
There is a difference between and ejector and an extractor, one will completely eject the empty,
the other ( and what the H&R will have ) will lift the Hull clear enough for you to manually extract.
With some practice and a slick chamber, a flick of the wrist back, and the hull should zip right out.
That's what you want, a smooth break and flick and your ready to drop in the next shell , snap shut & boom, repeat as necessary to the stage required shotgun shots.
I was given one in the seventies, 12 Gauge, case color, 28" blue barrel , some kinda lighter color hardwood stock.
I believe they were less than a $130.
Enjoy it, It's a great way to get Dad's and Granddad's legacy out and have fun too.
For you that is memories and Style.
I personally prefer a double, I learned on my Dad's Ithaca 12 Gauge , it was old then (mid 50's) probably circa 1920's...
( I did inherit the Rem. 870 Pump ) but we are not sure what ever happened to the old Ithaca Box lock double.
These days I use a TTn Colt 1878 hammered Double ( I enjoy the memories of a double and the style of a Mule ear shotty )