The two features were independent. Some had PC, but were sub-seconds (not SC), some were SC, but had no shock protection, some had both and some had neither.
Once Omega renumbered their calibers in then late 1940's, the "SC's" became cal. 28X and the sub-seconds became cal. 26X.
By that time, all of the 30mm movements had some type of shock protection, so the PC notation was obsolete.
Clear as mud, right?
gatorcpa
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