my question is, what do I do with them? Any ideas or suggestions?
Treasure them. Try to find out the story.
I killed my first deer about 10 with my grandfather's old shoot gun. A single barrel 16 ga. Fitting the description of the third gun you mentioned.
We weren't what you call rich. To hunt I had to walk a mile to the store picking up pop bottles to raise the funds. It cost $.25 for three shells. Yes you could by individual shells then. Not a lot of people had money.
The gun was old, a break open affair that required the spent shell to be pried out with a knife.
My grandfather was long gone then, but I started hearing stories about this gun. He pretty much fed his family during the depression with it. He had a part time job with the sheriffs department transporting prisoners from Perryville AR to Little Rock by wagon. It was the only firearm he had for the job. He lived about 11 miles east of Perryville, so he'd drive the wagon to town to pick up the prisoner, then back to the house where he'd spend the night for the all day trip the next day to Little Rock.
My uncle told me the story where he parked the bandit in a chair. Gave the gun to my grandmother (who was frail and stood about 4'10"). Told her to shoot him if he got out of the chair, while he took a nap. My grandmother parked herself in her rocking chair (which I also have) and covered the bandit.
The bad guy ask her, "you wouldn't really shoot me would you?". She says "get out of the chair and see". He didn't.
Years latter I lived in Portland. My mother and father we divorced and I lived with my father. When I was in HS, Id ride my motorcycle to Arkansas to spend the summer with my mother.
On one such trip I asked about the shotgun, I wanted it. My aunt had it but wouldn't let it go, said she needed it for protection. Though she never shot it, or even had shells, she needed it to scare people.
I convinced her a pistol would be better for her needs and told her I'd buy her one to trade for the shotgun. She agreed so I went to the hardware store and paid $29 for a pot metal RG or similar piece of crap. (Kids could buy guns in those days). I was afraid to shoot the thing so I didn't get her any ammo. But I got the gun now.
My grandfather use to load his own shells. Cast his slugs and used what ever he could find for shot. Later I found the gun was suppose to be for BP only but we didn't know about that stuff back then. We just shot what we could find.
I wouldn't shoot the thing now, Its too loose. Not front sight or bead, (didn't have one when I shot my first deer). To anyone else it wouldn't be worth the price to haul it to the dump, to me its Price Less.
Right now it rest on the horns of a deer my father's father shot during the depression in Idaho. That deer is another story altogether.
Grandpa's Gun
My first deer:
Blake Shelton - Granddaddy's Gun
https://www.youtube.com/watch?v=zFqdX-5W90U
I have a Model 28 S&W I was issued and carried in my 20 year LE Career. My department let me keep it when I retired. I just pray, some day when I'm long gone, it means as much to one of my grandkids as that old 16 ga. means to me.