What do I have here?

I was preparing to lace up a disc hub and assembling all the wheel parts. In my box of front wheel parts I found two lock rings, a new one in an Andover bag and labelled 060363 (correct) and a used one. The new one is 0.250 inch thick, but the used one is 0.467 inches. Too thick for a disc brake hub (or a drum brake for that matter). All Commandos, call for the same part number, but the Atlas has E6888. Probably the same part.

This thicker ring screws in perfectly, but is too thick. I can turn it down if I need to use it, but I'm curious what it fits and how I got it!

Anyone recognize it? (click on image for lager pic)

A bit of a guess Ron (because I haven't measured anything) but it's not a MkIII 850 rear wheel cush retaining ring that the flange has pulled off, is it ? It looks to have the unthreaded section where the flange is swaged on.

I think you nailed it 78x100! I noticed the unthreaded section and also noted on a spare MK3 hub that there was a flange on the bearing retainer, but didn't take off the retainer to look at how the flange was mounted. I assumed it was machined from one piece. Now that I see it was swaged on, I'm sure that is what this is.

Thanks!