I've got a "1 N" marked Colt CAR stock, $80 shipped. I've also got what might be the lockring you're talking about, it's the type with a single round hole instead of castle notches. If that's what you're looking for, I'll take another $7 for it (not sure if you need the nut or the ring).
PayPal is fine, no fee on this one.
Latch propped open to show the "1 N":