As to the inquiry about powder residue buildup underneath the ejector star, this can happen to any revolver with ammo that does not burn completely, or mostly completely in the barrel. The "Treasury load" 110 gr +P+ load was particularly miserable in that respect. To get to +P+ specs(there are no recgonized industry specs-only what the particular agency wanted) one had to use a fast burning ball powder and a lot of it. The result was a lot of unburned powder. And a lot of it migrated to all parts of the revolver, but under the ejector star was a place where it could be trapped, and it was.
I have a 3" and 4" CS-1, both were "overrun" guns. I have fired both of them extensively, I never used the +P+ load, but the "FBI" or "Chicago" load in .38 special 158gr SWCHP, or full house 125 gr .357 mag loads. The only time I had the powder buildup problem was when I used handloads of my own that used 2400 powder, which is very slow burning and should only be used in longer barrel guns or rifles. I used it because I had a lot of it on hand and got it cheap. So the idea is to use a powder that will burn rapidly for the barrel lenght concerned so there will not be any extra unburned powder to gum things up. Ball powder due to its shape is particularly bad when trapped under the ejector star. YMMV-but not much.
The CS-1 guns were great guns, and probably the best duty revolver that S&W turned out-not counting the N frame .357s of course.