The rifle was made before 1968 and has no serial number (shotguns and rimfire rifles weren't required to have serial numbers before 1968). The date code on the barrel indicates that it was made in March 1948. I'd rate it as NRA Very Good with an excellent bore. I put over 200 rounds through it today with only a couple failures to feed. One was with a CCI Mini Mag and one was with a Federal Champion. Incidentally, comparing the two types of ammo side by side they look identical except for the headstamp. They sound the same and shoot to the same POI at 25 yards. So, AFAIC, the Federal Champion is the equal of CCI Mini Mags. I also shot a bunch of Federal 550 bulk pack and it ran fine with them, too. (ATK owns both CCI and Federal.)
I ran a couple patches through the bore and applied a generous amount of FP10 to the bolt before shooting it. It hasn't been cleaned in a long time. For all I know there's four decades' worth of gunk inside the receiver. Fouling started working its way out of the action and some funk actually fell out the trigger slot. I took the stock off and removed the bolt, tonight and hosed the action out with Kroil, letting it soak for a couple hours. A fair amount of yucky stuff came out.
The 550-1 is a tackdriver. I shot it from the bench at 25 yards where it would keep the Mini Mags and Champions inside ~1.5" which is about as good as I can do with an open rear sight and a front bead. The receiver is neither grooved nor drilled and tapped for a scope. I plan to drill and tap the receiver with my milling machine. I have an extra Nikon 4x32mm Prostaff rimfire scope that will go on it.
The varnish on the stock shows some dings and chips, so I'll probably strip and refinish it. It's also missing the brass/gas deflector that Remington shipped with the rifles. Numrich has spares and the mounting screw, so I'll definitely get one. It does spit a little out the ejection port. I'll also probably swap out the recoil spring for a new one.
Compared with more recent .22 autoloading rifles the Remington feels a lot nicer. It's definitely a product of a bygone era when American gunmakers shipped rifles made from high quality blued steel with nice wood stocks. It feels a lot more solid than my Ruger 10/22 or the Marlin Model 60s I've handled.
I also shot my Remington Nylon 77 with the extra mags that I had to modify. (The 4 spare mags that I got from Remington would not lock into the rifle. I had to grind away part of the locking lug. Worse, 3 of the 4 needed the metal reinforcing clip bent out so I could load them.) They worked well today, so now I'm happy with them.
Here's a pic of the two Remington .22 autoloaders:
Older blued steel and walnut .22s like the 550-1 make excellent additions to any prepper's battery. They were made very well and in many cases are extremely accurate. Older Remingtons in particular have a reputation for being very, very accurate. The tubular magazine is much less likely to be lost than a detachable box, although if you aren't careful you can damage it.
Finally, I also put a box of WWB .45 ACP through my Springfield M1911A1 using two new Chip McCormick magazines, which worked perfectly.