The blue one is a 22lr and has a uncommon brass frame. Digging in my parts box produced a 22 mag cyl. that fits perfectly. Actually , it probably will not get used as I'm not a huge fan of convertible cylinders . It always requires some sight readjusting and I prefer set and forget.
Therefore the stainless one has only the 22 mag cyl. and has already earned a new set of flat bottomed grips.
Two guns for two cartridges.
My SS (OM, 1968) has both cylinders... but the Mag has permanent residence rights, while the LR hardly ever gets to come out of the box.
That's because of that H&R 999 Sportsman in the safe... that's my LR pistol!