Some discussion has happened here and elsewhere about the differences in the S and MS pistols brought in so far. I reached out to CZ and this was the reply, shared here.
The S models don’t have a “standard” configuration (not a cataloged item), the barrel might be configured 14x1 with and without bayonet lugs, as well as ½ x 28 barrels and 5/8 x 24, neither of which will accept bayonet lugs)
The 7.62 x 39 Ms models should be coming with 5/8 x 24 threads and no bayonet lug. The first shipments had 1/2 x28 threads.
The firing pin spring is included on all 5.56 models.
No firing pin spring was included on the full auto 7.62 x39 guns to prevent light strikes, I’m not sure, but if I had to guess, it is likely the S models in 7.62x39 were sold without a firing pin spring like the select fire guns, but they then added the springs back in on the MS guns.
The extractor cut outs were something only needed on the 7.62 x 39. (the extractor extends past the bolt head on the 7.62 x 39 extractor necessitating the additional clearance, whereas the 5.56 extractor has always been below flush.)
Hope that clears up a few things, if anyone was curious.
