Got these in a box of stuff if you know what they fit and can use them let me know I will pass them on.

The bottom one say 721 right on it, so my guess is a 721 Remington.

The top one? I don't know what it fits but it ain't much. If it where mine, I'd throw it in the scrap box.

Would a Remington 721 have such a small front receiver ring, or is it meant to touch just at the sides?

Whatever they are for, the top base seems to have a similarly small radius.

The bottom looks like a Carl Buehler base.

The bottom base looks like an old Redfield one-piece. They often stamped the model # on it. Likely a Rem 721. The radii on these is different as the rear receiver is flatter than the front. The top I have no clue.

The two bottom are definatly old Redfields. I have a number of those bases..If a base is marked 721 you can bet its a Rem mod. 721, but perhaps some have been modified, but I doubt that. Back in the day they shimmed and modified bases in order to center the cross hairs in the focal plane, so they centered when sighted in..some used shims and others used weld, paper match stick covers or whatever worked. those bases work with Leupold and Redfield rings and some others...

When dealing with old bases and rings, better install them to know if they work, a lot can happen when they are around that long, and idiots fix things. some with old guns that have been drilled and tapped for who knows what by some carpenter or mechanic, mabye a real estate saleman!

I believe there are only 2 bases pictured, top and bottom of each one.

Top one looks like it's for a pistol or maybe a 22lr.

On a related note, does anyone supply those rear adjustment/hold down screws loose? I looked everywhere and can't find anyone that does.

Russ,
Are you referring to the windage screws for the Redfield base in question?