Notes:

[0] Under U.S. law 27 C.F.R. § 479.102, the firearm is identified with a frame or receiver. Accordingly, the frame is not regarded as a spare part. Replacing a damaged frame is tantamount to creating a new gun with its identity due to the new frame. The old frame may be “demilled“ by cutting the frame into at least 3 pieces with ¼" of metal removed between each cut so that it can never be re-assembled. The remaining parts are exempt from federal regulation for domestic possession and trade.
    All gun frames made for sale are required to bear serial numbers. Obliterating or modifying this number is a federal crime. Most P210 frames are serially numbered en suite with the originally fitted slides and barrels. Some commercial commemorative pistols have unnumbered barrels. Early military and commercial pistols bear matching serial numbers on their hammer action casings.
    The slides and frames of the original P210 were machined from steel forgings. The frames of the first pistols designated SP47/8 are distinguished by their perpendicular angle of the trigger guard tangent line meeting the dust cover of the frame. This angle was changed to a backward slope early on in the production run. Starting in 1965, from serial number P 57001 onwards, the P210 frame was strengthened by reducing the amount of material milled away in the rear, in order to resist cracking reported by Swedish shooters. The Swedish shooting community enjoys access to hot Bofors M39B 9x19mm ammunition, banned from import to the U.S. owing to its unmatched capacity for penetrating body armor.
    Between 1983 and 1984, SIG introduced a new production series of the P210, switched over to Computerized Numerical Control (CNC) manufacture of major components. Starting gradually with the serial number P97601 and continuing with pistols serial numbered from P300001, frames milled out of 35mm steel plate stock replaced frames milled out of forgings. The CNC production run is distinguishable by an angled rather than a radiused transition from the frame dustcover to the frame rail housing, later on supplemented by a stepped reinforcement rib found under the frame rail housing aft of the slide stop hole. The lack of a matching relief cut machined in the new style slide stop pins prevents old style pins from seating all the way in the latest style frames.

    There are two kinds of factory frame finish. The glossy polished finish appears on P210-1 and P210-3 commercial variations and on the first, second, and third Swiss military contract deliveries, numbered from A100001 to A109710. Sandblasted finish appears on most commercial pistols made since the early Sixties, as well as on all pistols in the fourth Swiss military contract delivery, numbered from A109711 to A213110.

[1] The SIG P210 design is a licensed evolution of the 1935 S Petter pistol, in turn inspired by the Tokarev TT30, which at first was faithfully scaled up to 9x19mm Luger from the French chambering in 7.65x22mm Longue. Its additional design influence came from the Radom Vis wz. 1935, developed by Piotr Wilniewczyc and Jan Skrzypinski. Its main competitor was the Browning-Saive GP35 derivative, W+F 43 and W+F 47.
    On 19 May 1942, SIG tested five contemporaneous service handguns for accuracy in preparation for the development of their candidate for the next Swiss service sidearm, eventually adopted as the Pistole 49 and designated commercially as the P210. This is what they got in 8 shots fired at 50 meters:

• Walther P38:
  12.0cm from rest/14.5 cm offhand        
• Radom ViS35:
  18.5cm from rest/17.0 cm offhand        
• Colt M1911:
  30.0cm from rest/42.0 cm offhand        
• 9mm Luger 06/29:
  5.5cm from rest/11.5 cm offhand        
• 7.65 Luger 06/29:
  5.8cm from rest/9.0 cm offhand        

The test Colt was a 1919 commercial Government Model, SN C113936. (See Armbruster, p. 15.)
    In developing their improved version of the tilting barrel, short recoil locked breech autopistol design pioneered by Browning, Tokarev, and Petter, SIG engineers aimed at improving the performance of the M1911 at 50 meters sixfold, shrinking its 30.0cm 8 shot groups obtained in their machine rest tests, to less than 5cm, without compromising its ruggedness or reliability. To that end, 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.
    Unlike the frame of a handgun, its slide can be replaced without incurring legal restrictions under U.S. law. In a Browning design, tilting barrel short-recoil handgun, the slide is subjected to stresses that eventually cause it to crack. U.S. military M1911 and M1911A1 pistols are often found with their slides replaced by armorers around 30,000 to 60,000 round count. Later production slides are distinguished by additional heat treatment. That is also the case with P210 slides, which were often replaced in Danish military service due to firing high pressure submachine gun ammunition. Such replacement slides can be identified by their serial numbers struck with shallower numerals. Improved heat treatment appeared on P210 pistols made in mid-Sixties. It can often be identified by dimples from Rockwell hardness testing that appear on the polished lower surface of the breechblock inside the slide. When used with standard pressure 9mm Parabellum (Luger) ammunition, a hardened P210 slide can be expected to last well upwards of 100,000 rounds.
    Some military and commercial P210 pistols were made with extra “top ends” comprising slides and barrels in various barrel lengths and calibers, numbered en suite with the frame. If you have a set like that, please take care to keep it together.
    There are three kinds of factory slide finish. The polished finish appears on P210-1 and P210-3 commercial variations and on the first, second, and third Swiss military contract deliveries, numbered from A100001 to A109710. Brushed finish appears on most commercial pistols made between early Sixties and mid-Seventies; it was gradually phased out from the fourth Swiss military contract delivery, Ausführung (a), numbered from A109711 to circa A120500. Lastly, sand-blasted finish appears on late production commercial pistols and the fourth Swiss military contract delivery, Ausführung (b), numbered from circa A120500 to A213110.

[2] The Neuhausen design brief of building a Browning-style, short recoil, swinging barrel autopistol with the accuracy of a Luger, inspired key improvements of the pistol’s barrel. SIG engineers dispensed with the barrel swinging link, faithfully adapted by Charles Petter from the M1911. In the test prototype numbered 6004, SIG used two links pivoting around common upper and lower axes, for the sake of stabilizing the barrel trajectory during the cycling of the action. This costly and complicated arrangement was superseded in the test prototype numbered 6007, by incorporation of 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.
    The original centerfire P210 barrel profile features arched forward lower lugs. The arch contrasts with the perpendicular forward edge of the lower barrel lug that appears sporadically throughout the years of production, becoming standardized circa 1993. See Armbruster p. 81 featuring P210-5 P55185 and p. 144 featuring P210-S P59698, and Vetter p. 167 featuring P210-S P59700 and p. 168 featuring P210-5 P53675 and ”ab 1993 neueste Ausführung, Kante”.
    P210 barrels are machined out of steel forgings and rifled with a right hand twist, nominally measuring 1 turn in 250mm. They are designed to shoot standard Swiss Army pistol ammunition, the Pistolen Patrone 41, made by RUAG. This 124gr. FMJ 9x19mm round comes in 24-round boxes, which suffice to load three magazines. Like the RUAG rifle ammunition, it has replaced its original nickel alloy bullet jacket with a jacket made of copper. Its headstamps are the same as for the RUAG GP90 rifle round, comprising a T for the factory location in Thun, placed above the last two digits of the year of manufacture. The Pistolen Patrone 41 was originally produced for the P49. It is currently issued for the P75. Available for purchase at pistol ranges throughout Switzerland, unlike other RUAG ammunition, it is restricted from export. It is a high-pressure combat round, accurate albeit not optimized for target shooting.
    Like its slides, P210 barrels benefited from improvements in heat treatment introduced in the mid-Sixties. When used with jacketed ammunition equivalent to the Pistolen Patrone 41, a P210 barrel can be expected to retain its accuracy well upwards of 100,000 rounds. The standard barrel twist rate of the P210 is too fast to stabilize lead bullets. Barrels with rifling specially designed for lead bullets, with a twist rate of 1 turn in 500mm, are available as a drop-in option to fit any P210 irrespectively of its variation. In addition to the standard 120mm P210 barrels, there exist both blank and serially numbered 150mm and 180mm barrels chambered in 9x19mm with 6 grooves or in 7.65x21mm Parabellum (.30 Luger) with 4 grooves. The latter chambering requires an appropriately marked, lightened recoil spring assembly for reliable cycling with factory ammunition. The longer barrels are threaded at muzzle ends to accept special front sight mounts aligned by a Woodruff key and retained by nuts.
    The same three barrel lengths are available in the 6-groove .22 Long Rifle barrel with a twist rate of 1 turn in 450mm. The rimfire chambering mounts to the frame with a round slide stop hole in the lower barrel lug, causing it to maintain its axial alignment in the course of straight blowback action cycling. It comes as part of the .22 Long Rifle conversion kit that comprises a specially lowered lightweight slide, a light recoil spring, and one or two magazines with corrugated bodies, designed to position 8 slim rimfire rounds in the centerfire magazine well. A special short hammer assembly is available for accommodating the use of a rimfire conversion kit with adjustable sights.

[3] The designers of the Neuhausen pistol took as the starting point for its ignition system the licensed patents of Charles Petter. These patents in turn copied the 1930 Soviet Tokarev innovation of containing the hammer and its lockwork in a single assembly removable by hand for cleaning and maintenance. An ignition system built around a field replaceable unit construction hammer action makes the P210 easy to tune and maintain. The hammer action housing incorporates an integral ejector and retains its moving parts with friction-fit cylindrical pins. As a general rule, all such pins must be pushed out from the left to the right for removal. They must be reinstalled in reverse, using the same orientation and pushing from the right to the left.
    Early P210 hammer action casings were machined out of steel forgings. A cast hammer action housing made by Grünig and Elmiger replaced the forged part around the SN range of P311000 onwards.
    The P210 has a two stage trigger like the m/96 Mauser and the M1 Garand. It is characterized by two definite stages of travel, a relatively lengthy takeup followed by a crisp release. Most of the P210 hammer/sear engagement is released during the trigger takeup, as evidenced by the hammer retraction that takes place through the first stage of its trigger pull. The M1911 has a single stage trigger comparable to a single action revolver. In a single stage design the trigger is directly linked to the sear. As soon as the shooter’s trigger finger takes up the slack, the trigger starts moving the sear. Whereas in a two stage design the first stage completes the rearward movement of the hammer, whereupon the second stage of the trigger pull moves the sear to release the hammer. (The striker serves the same role in hammerless designs.) The single stage trigger pull design of a M1911 results in a mechanical compromise different from that of the double stage design of the P210. 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.

[4] There are two generic configurations of the P210 trigger: the standard reach “service trigger” with its forward curve shaped as an arc of a circle, and the short reach “sport trigger” with its forward curve resembling an arc of a parabola. This distinction is the most important visual cue for distinguishing the service model of the P210 from the sport model with the standard 120mm barrel. A small fraction of triggers was milled out of forgings and used in early military and sport pistols instead of the standard cast parts, differing from them in exhibiting fine polishing marks on their sides instead of the more common sandblasted finish. Early military style triggers exhibit minor differences in their shape and length of pull. A rare National Match style trigger is built with a stop screw accessible through the frame after stripping off the slide.
    The P210 trigger is made out of carbon steel finished in the raw. It will oxidize in service, gradually acquiring a gray patina. This patination can be used as a guide to the past use of the pistol, taking into account the likelihood of its retardation by periodic application of Automatenfett grease, or its reversal in a phosphoric acid bath.
    The P210 trigger impinges on the sear via the trigger bar that surrounds the magazine, part #26. It shares this method of connection with the M1911 and its derivatives such as the Tokarev TT30, the Radom Vis wz. 35, and the Petter M1935. Its direct connection compares favorably in its efficiency with angled levers employed in the Luger and the FN GP35, and lateral linkages characteristic of double action designs such as the Walther P38, or its own SIG P220 successor.
    The P210 trigger pivots on a staked pin, part #30. Its removal requires a special angled punch, and usually results in destroying the trigger pin. It is not required for normal maintenance of the pistol. However, the trigger spring, part #31, has an appreciable effect on the trigger pull. Its specifications differ between the service and the sport models. In a standard military issue P210, the permissible first stage weight may range between 2000 and 2500 grams. Replacing the trigger spring by a sport trigger spring (Sportsabzugsfeder) would reduce the trigger pressure by about 500 grams.

[5] Early P210 hammers omit the half-cock notch. In military service, such hammers appeared in the first and second Swiss military contract deliveries, numbered from A100001 to A107210. Most of these hammers were subsequently replaced with the definitive pattern that includes the half-cock notch, added as a safety measure. Pistols that remain in their original configuration command a premium.
    Second series hammers fitted since some point in the mid-Seventies are distinguished by a sear notch split by the stirrup cutout. This cutout stops short of the sear notch on the earlier hammers. This modification cured a design defect that caused damage on the edge of the sear notch in guns with high roud counts. At first, SIG would repair damaged hammers by grinding and heat treatment. When the trouble with the sear was seen to recur, enquiries employing high speed cameras captured the following sequence of events. After the shot was fired, the slide raced rearwards and cocked the hammer. Following the initial push by the slide, the hammer went down very fast and impacted against the edge of the double pull lever, part #21, before being pushed down again by the slide. In the long run, the blow against the double pull lever damaged the edge of the sear notch and degraded the trigger pull. Milling the slot in the hammer up to the surface of the sear notch allowed the hammer a longer way to travel and postponed the impact of the sear notch until the slide came back all the way. All Swiss army deliveries incorporated the first hammer pattern with an uninterrupted sear notch. The second pattern hammer appeared initially on the P210-5 and P210-6 sport pistols in the late Sixties. Eventually it was incorporated into all variants of the P210. See Vetter, p. 172 and Armbruster, p. 190.
    A special hammer for the rimfire conversion unit fitted with an adjustable micrometer rear sight features a cutout for clearance on the upper edge. Factory bobbed hammers were furnished on the P210-5 Sport and P210-7 Sport limited production guns. See Vetter, pp. 85, 124, 128, and 172. A rare National Match style hammer featuring a slim, solid tang can be seen in Armbruster, at pp. 111 and 190. Hammers on guns finished by Hämmerli typically bear that maker’s trademark or the capital letter H.
    Like its triggers and slide stops, P210 hammers are typically left in a natural raw finish that becomes patinated in use. The engraved and commemorative pistols are often furnished with triggers, slide stops, and hammers that are gold-plated everywhere except for their bearing surfaces.

[6] A significant flaw of the P210 design is that its safety locks only the trigger, leaving the firing pin free to move around. By contrast, the frame-mounted thumb safety lever on the M1911 and the GP35 blocks the sear. Additionally, the grip safety on the former pistol blocks the trigger until depressed. The Petter slide-mounted safety lever improves on these arrangements by locking the firing pin upon engagement. Additionally, automatic firing pin locks that disengage at the end of the rearward motion are incorporated in the Series 80 M1911 design by Colt and recent Mk III variation of the GP35 by FN. In this aspect, the P210 is inferior in security all of these pistols. Unfortunately, the unit construction of its hammer action group discourages any locking connection between the sear incorporated therein and the frame-mounted safety lever. The P210 is liable to discharge accidentally if it falls from a sufficient height on a sufficiently hard surface while a round is chambered, even if the safety is set. In our litigious society, this amounts to a serious safety issue. If you carry your P210, please make sure of its secure retention in the holster.
    Thumb pads with a smooth edge and grooves on their upper and lower flats appear on all safety levers in the first, second, and third Swiss military contract deliveries, numbered from A100001 to A109710, as well as on some safety levers in the fourth contract delivery, Ausführung (a), numbered from A109711 to circa A114000. All other safety levers feature grooved thumb pad edges and smooth upper and lower flats.
    All safety levers have hardened steel balls embedded into them under the thumb pad, at the point of contact with the frame. This ball wears a groove into the frame in the course of operating the safety. The safety lever can be removed from the frame by lifting it to the point where the ball detent slightly separates from the frame, and rotating it downwards. Negligent removal will result in extending the wear arc downwards, past the firing position detent dimple.

[7] Early slide stops in the first, second, and third Swiss military contract deliveries, as well as slide stops in the fourth contract delivery, Ausführung (a), numbered from A100001 to circa A120500, have flat checkered thumb pads. Fourth contract, Ausführung (b), numbered from circa A120500 to A213110, features a grooved thumb pad with a curved profile.
    The original design of the slide stop specifies integral construction milled out of a single piece of steel. This construction is retained in the second model of the slide stop with a curved thumb pad, distinguishable by a Rockwell hardness test mark on the side flat, atop the pin. The next issue features a two-piece construction, with the pin staked into the forged lever of the same curved profile. This construction can be detected by inspecting the surface of the slide stop under magnification, for evidence of a finely fitted circular gap about 4.4mm in diameter, located on the outer surface of the slide stop lever, and traces of tool marks inside it. Later on, a cast lever replaced the forged part. This construction can be detected by observing the finely cast sandblasted external surface of the slide stop lever, free of tool marks that characterize its predecessors, with a finely fitted circular gap about 3.7mm in diameter on the outward flat, and minute traces of casting flash inside it. See Vetter, p. 175. The final variation features a relief cut inside the lever on the collar that retains the pin, matching a reinforcing rib on the frame. This type of slide stop is the only one that fits late production frames distinguished by the presence of the reinforcing rib.
    Like the P210 hammer, its slide stop is finished in the raw and becomes patinated in use. Care must be exercised to avoid scratching the frame when removing or replacing the slide lever. A scratch appearing on the frame under the slide lever attests to negligent maintenance.

[8] The magazine safety device of the P210 in no way interferes with its trigger pull. It comprises a wedge at the end of a leaf spring, held down by a screw, part #35, which springs the trigger rod, part #26, out of its engagement with the sear, part #23, whenever the magazine is removed from the grip frame. Once the magazine has been inserted in its well, the top of its body springs aside the wedge of the magazine safety, enabling the trigger spring, part #31, to push the trigger rod upwards, connecting it with the sear. At this point, the magazine safety device does not make any contact with the firing mechanism. This fact can be readily ascertained by observing the operation of the hammer action after removing the grips.
    The magazine safety device may be dismantled by removing the grip plates, parts #36 and #37, and unscrewing its retaining screw, part #35. It is reinstalled in the reverse order of the dismantling, ensuring that the screw is properly tightened and verifying the springing of the trigger rod, part #26, by the magazine safety device.

[9] The double pull lever is the part responsible for regulating the transition between the two stages of the trigger pull of the P210. After the trigger, part #28, takes up the slack to engage the sear, part #23, by way of the trigger rod, part #26, the first stage of the trigger pull is determined mainly by the weight of the trigger spring, part #31, with additional resistance provided by the sear spring, part #24. As the sear rotates around its pin, part #22, it brings all the way back the hammer, part #14, and contacts the double pull lever, part #21. At that point, the double pull lever connects the sear with the mainspring, part #20, providing considerable additional resistance in the second and final stage of the trigger pull, just before the release of the hammer by the sear.     The double pull lever is individually hand-fitted to the sear and the hammer to regulate the pressure point (Druckpunkt) of the two-stage trigger pull system. If the pressure point is too soft, i.e. if the second stage of the trigger pull has to be strengthened, the top surfaces of two support arms furthest away from the pivot pin of the double pull lever, part #22, must be evenly worked down with an oilstone at the point of their contact with the hammer action housing, part #13. This operation brings the body of the double pull lever closer to the sear. In performing this operation, both sides of the double pull lever must remain perfectly square at the points of their contact with the hammer action housing. The hammer action housing itself should not be modified. If the pressure point is too hard, i.e. if the second stage of the trigger pull has to be weakened, the two projections in the middle of the double pull lever located on either side of the stirrup, part #16, must be evenly worked down with an oilstone at the point of their engagement by the sear, part #23, in the course of the trigger pull. This operation postpones the engagement of the double pull lever by the sear. In performing this operation, both projections on the double pull lever must remain perfectly square at the points of their contact with the sear. The sear itself should not be modified. Never attempt any modification of these parts, unless you are certain of your gunsmithing competence.
    In late production, forged and deep hardened milspec sears and double pull levers were gradually replaced by metal injection molded (MIM) parts of slightly modified profiles. This image is taken from Armbruster, p. 193: As with all MIM components, these parts are superficially case hardened. They are therefore unsuitable for hand fitting that is liable to cut through the hardening and expose soft core metal in the working surfaces.

[10] Early Neuhausen pistols numbered from 6030 to 6924 were made with the firing pin held in place by a firing pin retaining pin. Later production centerfire pistols abandoned this retention system in favor of adopting an M1911-style firing pin retaining plate, part #5. All rimfire slides continued to use the firing pin retaining pin system.
    The P210 firing pin is made out of hardened steel in a stepped configuration. It is of an inertial design, and does not touch the primer of the chambered cartridge with the hammer down. It may be removed by depressing it through the firing pin plate, part #5, with the end of the slide stop pin, part #40, and sliding the firing pin plate out of its slot in the slide. The firing pin channel in the slide should be cleaned out and lubricated periodically. Reinstall the firing pin in the reverse order, by sliding the firing pin plate into its slot in the slide, whilst pressing the firing pin down into its channel with the slide stop pin. In pistols that use the firing pin retaining pin system, the retaining pin must be drifted out from the left to the right and reinstalled from the right to the left in the same orientation.

[11] The pivoting extractor of the P210 follows the Petter design by operating on the principle of the Colt M1903/1908, FN Browning M1910, and Tokarev TT-30, in contrast to the spring tensioned extractor featured on the FN Browning M1900 and Colt M1911. This extraction system is more durable and reliable than the self-sprung M1911 design. The M1911 action is designed to pick up rounds only from a loaded magazine, controlling their travel throughout the operating cycle. While slamming the slide home on an empty chamber does not stress the M1911 extractor, the most common cause of its breakage originates from slamming the slide home to snap over a round hand-loaded into the chamber. The amount of pressure that a M1911 extractor places on the rim of a cartridge casing is regulated only by its curvature in the part that passes through the extractor channel in the slide. Too much curvature causes excessive pressure, whereby the extractor prevents the cartridge casing from chambering, resulting in a failure to feed. Not enough curvature causes insufficient extractor tension, resulting in failures to extract the spent casing fully or to eject it. As with its unit construction hammer group, the pivoting spring-loaded extractor of the P210 follows the Tokarev pattern by relegating the control of extractor tension to a separate coil spring. This division of labor improves reliability and serviceability and enables the extractor to snap over a cartridge dropped into the chamber without undue stress.

[12] SIG zeroes the P210 with Swiss military issue ammunition with a point of impact placed 10cm above the point of aim in order to allow a six o’clock hold on the standard target. SIG zeroes the pistols individually and in most cases installs a front sight marked with the letter N. This sight has a post 5.9 mm tall. The sight nomenclature and markings are as follows:

• Nr. 4:
  5.20 mm / -...        
• Nr. 2:
  5.50 mm / -.          
• Nr. 1:
  5.70 mm / -           
• Nr. 3:
  5.90 mm / N          
• Nr. 5:
  6.10 mm / +           
• Nr. 6:
  6.30 mm / +.          
• Nr. 7:
  6.50 mm / +..         

Standard and contrast front sights are made in eight heights ranging in from 5.10 mm to 6.50 mm in 0.20 mm increments, with matching standard and contrast rear sights. Click-adjustable rear sights are matched by front sights that exist in four heights ranging in from 7.50 mm to 9.00 mm in 0.50 mm increments. Different front sight pushers are made for the standard pistol, the extended barrel, and the rimfire conversion kit. In servicing sights, the dovetailed parts must be pushed out from the left to the right and reinstalled from the right to the left. Fixed sights on the P210 can be regulated for windage or elevation with the front sight pusher, by moving the front sight blade sideways or replacing it with a blade of a different height.

[13] Factory fixed sights for the P210 come in two patterns The military sight with a rounded U-notch is meant to match a narrow front sight of a sloping, serrated profile. The contrast sight of the bar pattern patented by Georg von Stavenhagen as U.S. Patent 3,192,632 on 6 July 1965, is meant to match a wider, Patrige-type post front sight.
The factory micrometer rear sight for the P210 is designed to fit in the same dovetail as the fixed rear sight. It presents a good sight picture but sits high on the slide, getting in the way of gripping its serrations. As illustrated in the factory parts diagram, the elevation screw (Höhenstellschraube, #55) on the factory adjustable "micrometer" rear sight is turned down 4 full turns in a shooting setting zeroed for 25 yards. With a higher setting suitable for 50 meter ranges, the shooter may experience this screw backing out under recoil. Nonetheless, with a properly machined rear sight, the steel ball (Stahlkugel, #51) and the elevation spring (Höhenfeder, #58) should be held captive by the rear sight body (Visierblatt, #50). Unless the elevation screw pops out free of the threads in the sight base (Visierfuss, #54), the micrometer rear sight assembly should stay in one piece, provided that the free length of the spring and its rate are in spec.
Since 1 January 2007, factory micrometer sights have been approved for use in the Swiss service pistol competitions. On 1 January 2009 this approval extended to the new micrometer rear sight assembly made by Swiss gunsmith Stefan Dobler. Dobler’s sight is distinguished by compact dimensions that eliminate the overhang of the sight blade above the hammer cutout in the slide. Aftermarket products by LPA are restricted to specialty events like ISSF matches category centerfire. By contrast, they are allowed and used to advantage in a broader range of German shooting events.
Shooters who need to accommodate several loads might be well served by a new model of adjustable rear sights for the SIG P 210 pistols presented at the IWA 2008 by SIG Sauer. This unit is claimed to fit into the standard dovetail and work with three different positions for static-precision disciplines or PPC 1500. It allows to zero in the pistol on three different ranges, then choosing between them via a simple 3-position slider. The new open sights comes with a new front sight and two different rear sight slides, one for precision-disciplines, the other for PPC 1500. An Aristocrat Tri-Set rear sight with three settings to lock different elevations, operating on a similar principle, has been adapted to the P210 in the past. A more sophisticated version of the same design is made by Leon Crottet, the gunsmith responsible for the development of the factory version of the P210 lateral button magazine release. This click-adjustable rear sight assembly is inletted into the slide for a low sighting line. Except for the earliest, low-mount variation of their design, which pivoted off an axis milled into the slide, that is not the way that the Neuhausen factory has made its handguns.

[14] The earliest SP47/8 magazines differ in lacking the crimp on the upper left hand side of their body and the matching relief cut in the magazine follower, as found in the subsequent pieces. There exist three kinds of P210 magazines. Early milspec magazine bodies, manufactured for SIG by MecGar, are of seamless construction. More recent magazines, manufactured by SIG Sauer, are folded in the back in a dovetail pattern. See Vetter, pp. 170-171.
Lastly, the magazines retained by the lateral button latch of the P210-8, P210-6S, and P210-5LS can be recognized by the corresponding cutout in the magazine body. These magazines are equipped with ergonomically extended, cast steel floorplates.

[15] The first P210 variants featured walnut stocks with horizontal grooves. Later pistols utilized black plastic grips with a molded checkering pattern or black walnut stocks with hand-cut checkering. Special National Match stocks, sometimes found on the so designated Sixties and Seventies heavy frame pistols and their conventional contemporaries, extend the backstrap downwards in a straight line to cover the magazine catch. Various patterns of carved walnut stocks, with or without a lanyard loop cutout, can be found complementing the engraved P210-L “Luxus” pistols. Special editions of P210 pistols are often found with stocks carved out of wood or molded out of Galalith, secured in the backstrap with a flush-fitting vertical lever pivoting on one concealed Philips head screw attached on the bottom of the stocks and engaging three others screwed in higher up. See Armbruster, p. 176 and Vetter, pp. 176-177.

[16] There are several types of recoil springs fitted to the P210. All of them are fitted onto a two-piece, full-length guide rod held together with a solid transverse pin. The standard spring has a preload of 2.5kg and 4.8kg with the slide drawn to the far rear position. This spring has no special markings. Besides the standard spring there is also a special spring for use with the drop-in barrel chambered for the 7.65x21.5mm Parabellum cartridge, marked “7,65”. Another one goes with the .22 set, being so marked. A special strong spring was furnished for Scandinavian and Finnish orders. It is marked “9,0 S”. The preload of this spring is 3.4kg and 7.3kg with the slide drawn to the far rear position.

[17] Although the P210 heel magazine catch may seem cumbersome in operation, it is far less prone to accidental release during carry than the side-mounted button of the Colt M1911 and Browning GP35. Many competitive shooters find it an impediment to using the P210 in timed events that require rapid reloads. But for defensive use, reliable and consistent magazine positioning and retention is by far the most significant parameter affecting semiauto pistol reliability. As witness a comparison of the bearing surfaces, the heel latch system ensures it better than the vast majority of alternative designs.
    The loop of the P210 magazine catch is liable to break off when the pistol is used for a buttstroke against a rocky noggin, or fired braced off a hard rest. The extended magazine floorplate, made and sold by Karl Nill, affords the preferred solution to this predicament.