"Right regarding the sizes, but the manufacturer lists 242 as "medium strength" and 222 as "low strength".
It's important that with any application that the threads be free of grease/oil."
I always clean the threads with alcohol, lighter fluid, acetone, etc. With the LCR I went easy on the female threads because I didn't want to leave any traces of paper towel in there. The Ruger tech advised against Loctite, but use it lightly if necessary...that was to make it easier on them if they ever need to disassemble it.
Back to the low strength purple stuff, I was thinking it might also be a thinner mixture which would work better with the smaller threads. I've never used it, but will get some and try it on the 10 if the 242 blue fails and the thumbpiece backs off again.
Both male and female threads on the thumbpiece looked just fine.
I've seen a lot of buggered up thumbpiece nut slots on GunBroker.