More detail, including parts diagrams, here on the design and development history of the P210.
https://larvatus.livejournal.com/182532.html
some accuracy improvement highlights:
they reversed the customary rail interface between the slide and frame from its prototype designed by Browning and patented by him as U.S. Patent 580924. Whereas previous slides incorporated rails that aimed inward, towards each other, and reciprocated on tracks cut into the frame, the slide of the P210 mimicked the arrangement of the Luger receiver that reciprocated within the frame. As with the Luger, the P210 frame tracks were located on the inside, whereas its slide rails faced outwards, away from each other. SIG designers also dispensed with the barrel bushing, as used by all three of their predecessors, Browning, Tokarev, and Petter. In its stead they used a solid slide with a differentially bored opening at the business end, allowing the barrel to drop down at the breech while minimizing play at the muzzle.
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SIG engineers dispensed with the barrel swinging link.....two precisely milled surfaces, a locking device slot (Verriegelungsnut), inspired by the corresponding features of the Radom Vis, and twin locking device curves (Verriegelungskurven), protected under Swiss Patent No. 270873. This arrangement allowed the barrel to remain coupled to the slide in cycling under recoil, until the bullet left the bore, whereupon the chamber started to drop for unlocking the action.
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The limiting factor in a single stage trigger in a self-loading handgun is the depth of sear engagement required for safe operation in self-loading action. In a double stage trigger such as is used in the SIG P210, the sear engagement between 0.5mm and 1mm (0.02" to 0.04") leaves an adequate safety margin when the action cycles. But in the second stage of the trigger pull the sear engagement is only 0.05mm (0.002"), causing next to no creep. Whereas a M1911 must have its sear engagement of at least 0.4 mm (0.016") to prevent the hammer from following the slide in cycling. Consequently, its trigger has to creep an order of magnitude more than the second stage in a double stage design. Conversely, a traditional double stage trigger enables a deeper sear engagement to be combined with a crisper release in repeating firearm designs.
