Michael Zeleny (larvatus) wrote,
Michael Zeleny

sig p210 heavy frame development i

The Schweizerische Industrie-Gesellschaft, or the Swiss Industrial Society, commonly known as SIG, and located in Neuhausen am Rheinfall, stands alone among the manufacturers of small arms in having designed and produced the only sidearm ever to be adopted for military and constabulary service that was meant to be equally well suited for bullseye competition. While early service-grade sidearms such as the C96 Mauser and various variants of the Borchardt-Luger pattern are capable of equal or better accuracy, this degree of precision in bullseye performance was incidental to their design brief. Whereas the requirements of the Swiss Army that led to its adoption of the SIG SP47/8 pistol as its Pistole 49, expressly incorporated a stringent standard of accuracy in formal 50 meter bullseye competition.

Commercial Swiss market SIG SP47/8 compared to the 1st KTA contract SIG P49:

Contrast the hooked front sight (Hakenkorn) on the SP47/8 (below) with the ramp front sight on the P49 (above); note the transverse firing pin retainer and loaded chamber indicator pins on the SP47/8 and the lanyard loop added on the P49.

Note the loaded chamber indicator on the SP47/8 (left) and the grip grooves reaching around the grip on the P49 (right).

Note the firing pin retainer plate on the P49 (right).

Contrast the sloping front of the trigger guard on the P49 (above) with the plunging front of the trigger guard on the SP47/8 (below).

Contrast the sloping front of the trigger guard on the P49 (above) with the plunging front of the trigger guard on the SP47/8 (below).

Slide numbered under the breech block on the SP47/8; no Rockwell test dimple.

Slide unnumbered under the breech block on the P49; Rockwell test dimple present; firing pin retainer plate visible.

Unnumbered breech block on the P49 with a Rockwell test dimple and firing pin retainer plate visible(left); numbered breech block on the SP47/8 without a Rockwell test dimple (right).

Hammer actions of the P49 (left) and SP47/8 (right) are of identical construction; both incorporate a shoulder in the rear, deleted in subsequent P210 models.

Thus it is noteworthy that it took SIG all of twenty years after developing the SP47/8, to introduce its first dedicated target pistol, the P210-5. Lorenz Vetter shows two P210-5 prototypes made by SIG in 1967. Both had slides marked as SP47/8 „Sport“, with forward slide rails milled down and frames that accepted hammer actions with rear shoulders, as per the pattern of the SP47/8 repeated in the early military and commercial P210 variants. But otherwise these pistols were constructed in the definitive P210 fashion, with trigger guards sloped back and firing pins retained by plates in the rear. Both of them omitted front sight dovetails, in a gesture of dedication to the long barrels supporting the front sight in a carrier mounted at the muzzle. The pistol numbered P52221 was fitted with two blued 150mm barrels chambered in 7.65mm Para and 9mm Para, bearing standard military sights in P210-5 type carriers, mated with the standard military rear sight mounted in a dovetail on the slide. The pistol numbered P52222 was fitted with a bright polished 180mm barrel chambered in 9mm Para and a blued 150mm barrel chambered in 7.65mm Para, and bearing standard military sights in P210-5 type carriers, mated with a low profile screw adjustable rear sight pivoting on a transverse pin located in the slide.

Meant as a limited production special offering to its more competitive customers, the P210-5 was initially delivered between 1967 and 1975. In outward appearance, it was distinguished by a 150 mm long barrel, exceeding by 30 mm the standard 120 mm barrel, a dimension that SIG inherited along with its characteristic outboard frame rails from the Luger variants that preceded it in Swiss military service. The long barrel was mated with a standard profile slide, allowing for an extended 202 mm line of sight, compared to 164 mm in the basic service type models. A flat cover plate filled the standard front sight dovetail cut in the slide. The tall Patridge type front sight, mated to the micrometer rear sight, was available in four heights ranging in from 7.50 mm to 9.00 mm in 0.50 mm increments, as against five alternatively sized military sloped and ribbed blade front sights mated with a U-notch rear sight, or contrast von Stavenhagen type white dotted post front sights that were made in eight heights ranging in from 5.10 mm to 6.50 mm in 0.20 mm increments, to be mated with a square notch rear sight marked with a white post. The Patridge front sight of the P210-5 was mounted in a dovetail cut into a tubular carrier located around the muzzle end of the barrel with two steel nuts bearing against two polymer washers, and aligned to it with a Woodruff key mating with a longitudinal groove in the barrel to prevent radial play. Like the subsequently introduced P210-6 sport model, the P210-5 target pistol was equipped with an adjustable trigger stop, an Allen bolt screwed into the frame behind the trigger guard, and accessible from the rear of the frame after removing the grips and the hammer action. It also shared with the P210-6 a sport trigger of a special hooked profile, shortening the length of pull and encouraging a more consistent positioning of the trigger finger. Like all SIG pistols, it can be fitted with a drop-in factory barrel chambered in 7.65mm or 9mm Parabellum.

The internal differences of the SIG P210-5 were equally significant to the target shooting design brief. Historically, SIG strove to maintain as much compatibility as possible between the internal parts of its P210, so that they could be interchanged between different variants regardless of their production dates, on a drop-in basis. This compatibility does not and cannot extend to the internal parts of the hammer action, which must be hand-fitted to each other to optimize the tactile quality of the trigger pull. Moreover, while a spare hammer action can be dropped into a military grade P49 without any loss of functionality or mechanical accuracy, this degree of convenience, meant to cater to the needs of the unit level armorer, comes at a cost to the dedicated target shooter. Unlike mechanical accuracy measurable by the maximum spread of bullet impact points of service grade ammunition fired out of the pistol secured at its grip frame in a machine rest at a target located 50 meters away, practical accuracy achievable in freehand shooting at the same target depends critically on the quality and consistency of the trigger pull. In turn, the quality and consistency of the trigger pull depends critically on a constant relation between the moving parts of the firing system, such as the trigger connected by way of the trigger rod to the sear that trips the cocked hammer to ignite the cartridge via the firing pin, and thereby release the shot. In the P49 design, this relation varies by design in the degree of play allowed by the clearances between the body of the hammer action and its receptacle in the frame, required to enable its removal and reinstallation by hand. In a dedicated target pistol, this modularity can and should be sacrificed for the sake of precision tuning for repeatable ergonomic quality of the trigger pull. To accommodate this desideratum in the modular design of the SIG P210, early P210-5 variants featured a hammer action fixed to the frame with a plug screw on the left hand side reaching into the inspection window of the hammer action to hold it down. Later on, SIG relocated the hammer action retaining screw to its familiar position under the frame tang, screwing into a threaded hole in the rear slope of the hammer action.

Adapting the P49 to the needs of target shooting required another set of compromises. There are two ways to build a safety margin into a self-loading action. The sear engagement has to be long enough to provide a safety margin against the jostling in the firing cycle, so you either lengthen it in a single stage (as in the M1911) or build a two-stage trigger with a longish stroke completing the cocking action followed by a very crisp letoff (as in the P08 and P210, or the m/96 Mauser and M1 Garand). As a consequence of their design, two-stage designs require a longer reset. They are popular in bullseye competition, where the stage transition allows the shooter to reacquire his target just before he releases the shot. Likewise, they are well-suited to military and constabulary service, where the first stage of the trigger pull provides a margin of safety against combat-induced twitching.

Thus the SIG P210 has a two stage trigger, 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, so that the trigger starts moving the sear as soon as the shooter’s trigger finger takes up the slack. 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.) Additionally, the P210 differs from the M1911 in having its trigger pivot on a pin rather than slide in a channel. This method of operation reduces lateral play and results in a smoother sear engagement.

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 greater than the second stage in a double stage design. That is why both bullseye shooters and military procurement agencies tend to favor two stage trigger designs.

The unit construction hammer action, derived from Charles Petter’s 1935 design licensed by SIG, incorporated a two-stage trigger pull lever (Druckpunkthebel) as an original contribution by SIG designer Max Müller. This lever is the part responsible for regulating the transition between the two stages of the trigger pull of the P210.

Hammer cocked, trigger in resting position, as illustrated by Pierre Hirschy in the 1966 Die mm Pistole 9 (Pis. 49) Anleitung für die Waffenmechaniker.
8 Trigger
15 Hammer
17 Sear
18 Pressure point lever
42 Trigger bar

Upon pulling the trigger, the trigger rod pinned to it and sprung against it slides rearwards, engaging its notch against the notch at the end of the sear. In turn the sear pivots on its pin and reduces its engagement with the hammer. Shortly before the hammer can be released from the sear, the sear bears against the pressure point lever and increases the resistance to the trigger finger. After the trigger finger overcomes the palpable increase in resistance (pressure point), the hammer releases itself from the sear, accelerates forward under the power of the mainspring, and strikes the protruding end of the firing pin. The firing pin tip hits the cartridge primer and fires the shot.

Pressure point control, the sear bears upon the pressure point lever.
8 Trigger
15 Hammer
17 Sear
18 Pressure point lever
42 Trigger rod

The hammer is recocked when the slide is recoils rearwards; it snaps back into place on the sear. At the same time, the trigger rod is pushed down by the slide, and its connection to the sear is interrupted. The next shot can only be fired after the trigger has been released and the sear reconnects to the trigger by way of the trigger rod.

After the trigger takes up the slack to engage the sear by way of the trigger rod, the first stage of the trigger pull is determined mainly by the weight of the trigger spring, with additional resistance provided by the sear spring. As the sear rotates around its pin, it brings the hammer all the way back, and contacts the pressure point lever. At that point, the pressure point lever connects the sear with the mainspring, 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 pressure point lever is individually hand-fitted to the sear and the hammer to regulate the pressure point (Druckpunkt) of the two-stage trigger pull system. The weight of the second stage of the trigger pull varies inversely with the height of two support arms furthest away from the pivot pin of the pressure point lever that serve to distance it from the sear. It also varies directly with the height of the two projections in the middle of the pressure point lever located on either side of the stirrup, which postpone the engagement of the pressure point lever by the sear. Accordingly, the target and sport pistols, P210-5 and P210-6, featured a pressure point lever reshaped to adapt the trigger pressure stage transition to the task of deliberate slow fire at stationary targets.

P49 pressure point lever (left) compared to P210-5/6 pressure point lever (right).

According to H.P. Doebeli’s report of the company records, the production of the first run of the P210-5 was officially discontinued in 1975, after a total of approximately 3294 pistols have been manufactured. The last of them was numbered P79000. As a successor to the P210-5, starting in 1974 SIG offered the dedicated target pistol P240 co-branded with Hämmerli. The SIG-Hämmerli P240 was built on a Browning-Petter-Müller type swinging barrel short recoil locked breech action, and chambered in .38 S&W Special Wadcutter. Two years later, it was complemented by straight blowback P240 variants chambered in .32 S&W Long Wadcutter and .22LR. The P240 lacked one definitive characteristic of the P210, its unit construction hammer action. Instead, it offered screw adjustments for the trigger pull weight, the trigger spring preload, the trigger bar engagement, and the hammer-sear engagement, though all but the first were factory set and Hämmerli advised the end users against adjusting them.

Original production run 9mm Para SIG P210-5 serial number P65367, proofed in Germany in 1973.

Nevertheless, SIG continued sporadically to mate standard P210-6 frames with P210-5 pattern top ends featuring 150mm barrels into the late Seventies and early Eighties. The batch production of the P210-5 resumed after the 1983/84 transition, from milling the frames out of forging, to CNC machining them out of bar stock. Starting in the late Eighties, SIG offered its P210-5 with an extra long 180mm barrel, complementing it with an optional, similarly dimensioned .22LR conversion kit. Both the P210-5 and its much more common sibling, the P210-6, achieved considerable renown among bullseye shooters. Less well known is their distinction in action shooting events. Thus Jan Foss of Norway won the IPSC 1976 World Shoot II in Salzburg, Austria with his 9mm Sig P210, beating the previous year’s champion, Ray Chapman of the United States wielding his .45 ACP Government Model Colt customized by Pachmayr Gunworks. And in 1977, Vidar Nakling of Norway took the fourth place with a SIG P210 in 9x19mm minor. But it is safe to assume that most owners of these pistols acquired them as Veblen goods purpose-built for manly men. The heavy frame variants sat on the next rung on the ladder of conspicuous consumption.

National Match 7.65mm Para SIG P210-5 heavy frame serial number P59707; note the extended, coarsely checkered target grips with grooves for the thumb and the index finger, and the extended 150mm barrel to be inherited by the standard P210-5:

The trigger of the National Match pistol exhibits characteristic longitudinal grooves, compared to the smooth surface of the milled target trigger on the initial production run of the standard P210-5. The reinforcement of the heavy frame can be readily seen in the profiles if the dust cover under the frame rail housing, compared to the frame of the 9mm Para SIG P210-5 standard frame serial number P65367:

Note the thick walls of the dust cover of the heavy frame:

Frame reinforcement continues to the tang of the frame on the right hand side:

The windage adjustment screw of the micrometer rear sight on the National Match pistol is oversized in comparison to its counterpart on the initial production run of the standard P210-5:

Frame reinforcement has to be interrupted on the left hand side in order to accommodate the slide stop and safety levers; note also the threaded opening on the National Match pistol to accommodate a threaded peg fitting in the inspection hole of the hammer action to secure it on the left hand side:

The SIG P210 Heavy Frame pistol emerged as a subvariant of the P210-5. In 1965/66, SIG adapted the P210-5, itself derived from Swiss military P49 pistol, for bullseye competition by the members of the A-Match group of the Schweizerischen Match-Schützenverbandes, the Swiss Match Shooting Federation (SMSV). The main characteristics of this “Nationalmannschafts-SIG” or National Match Team SIG Pistol were a reinforced, heavier grip, a slightly slimmer, grooved, milled trigger, and enlarged micrometer rear sight adjusting screws, marked with the letters “H” and “R”. In addition, these pistols, produced in only a small number, were equipped with specially designed coarsely checkered oiled walnut grips, which were extended to the rear and provided with lateral grooves for the index finger and the thumb. In his 1992 DWJ article dedicated to the heavy frame variants of the SIG P210, Robert R. Field allows that reducing the risk of possible cracking may have originally inspired their development, given the high round counts expected of the weapons of the A-squad of the SMSV. However, he also points out that firing 100,000 to 120,000 rounds of the high pressure Swiss Army PP41 9mm Para ammunition in the standard frame configuration, yielded cracks in but one in a thousand pistols. Putting more weight into the frame to stabilize off-hand aiming and dampen the vibration of the self-loading action may have served as an additional motivation for this development. Notwithstanding such speculative guesswork, all observed forged heavy frame pistols are distinguished by their “best of the best” quality of fit, finish, and final adjustment that befits their rarity.

Between 1967 and 1972, SIG delivered 58 national match team pistols to the SMSV. These deliveries included 12 normal P210-5 pistols built on a standard dimensioned frame, and meant for the B-Squad of the SMSV pistol, as well as 38 P210-5 Heavy Frame pistols that were meant for the A-Squad of the Pistol Match Group. Eight more of the heavy-frame pistols were sold elsewhere. H.P. Doebeli reports the following information as taken from the Inventory List of the “Gruppenchefs Pistole SMSV”, dated 28 February 1974. SIG checked and confirmed this inventory list on 6 January 1975.
Serial Number Delivery Date
P52222 8 June 1967
P52235 8 June 1967
P56841-P56846 8 June 1967
P57843 3 April 1965
P57847-P57835 18 May 1965 - 8 June 1967
P57850 12 May 1965
P57909 11 March 1966
P57911 28 May 1966
P58931-P58933 31 March 1966
P58934-P58936 30 March 1966
P58937 25 April 1966
P58938 25 May 1966
P58939 15 June 1966
P58940 10 May 1966
P59701-P59704 17 February 1967
P59705 21 February 1967
P59707, P59708 6 July 1967
P59709 21 February 1967
P59710 12 December 1967
P60431-P60436 31 January 1969
P60437 31 January 1967
P60438-P60449 31 January 1969
P60899, P60900 10 February 1971
P66383-P65385 2 February 1972

The following serial numbers from the foregoing list belong to National Match Heavy Frame pistols: P52240, P54980, P56841-P56846, P57847-P57849, and P59701-P59705. The total number of National Match Heavy Frame pistols, both officially delivered and privately sold, adds up to 46. Thus Heavy Frame National Match variants included 7.65 Para pistols with serial numbers P58931-P57933 and P60431-P60448, delivered to SMSV from 1966 to 1969. In March 1975, SIG delivered to Hofmann & Reinhart 25 commercial 7.65 Para P210-6 Heavy Frame pistols with serial numbers from P79101 to P79125 and another 25 commercial 9mm Para P210-6 pistols with serial numbers from P79126 to P79150. All of these pistols featured milled triggers. Additionally, most of them featured special National Match hammers, ground to special slim shapes to reduce lock time. In subsequent production, a similarly motivated Sport hammer option featured a cutout in the face of the standard hammer, meant also to clear the factory micrometer rear sight mounted on the lower profile blowback slide of the rimfire conversion kit.

Various P210 hammers: military (left); Sport (center); National Match (right).

Curiously enough, the one SIG P210 development that can be inferred to accommodate high round counts appeared only in late CNC frame series production, when all hammers were modified to interrupt the full cock sear notch, allowing free passage past the stirrup in overtravel caused by the rapid fire use of ammunition that yielded an increased recoil impulse.

Standard P210 hammer (left) and late production hammer with the sear notch interrupted to clear the stirrup in overtravel (right).

Having developed the Heavy Frame option for the National Match team, SIG proceeded to commercialize it in limited production runs. Between May and June 1979, SIG released a series of 100 P210-6 Heavy Frame pistols, serial numbered between P76521 and P76620, all fitted with milled triggers. Another series of 50 P210-6 Heavy Frame pistols, retailed by Hofmann & Reinhart of Zürich and serial numbered from SN P79101 to 79150, had its first half chambered in 7.65mm Para and the rest in 9mm Para, all built on a National Match frame with a threaded opening on the left hand side aft of the safety lever pivot, to accommodate a threaded peg fitting in the inspection hole of the hammer action, and fitted with military drift-adjustable sights and milled sport triggers. Illustrated below is the penultimate pistol from the Hofmann & Reinhart series.

The last series of P210-6 Heavy Frame pistols, serial numbered between P79621 and P79720, all fitted with cast sport triggers and Patridge front and standard micrometer rear sights, and omitting the threaded lateral opening, was delivered before the end of 1979. As documented by H.P. Doebeli and Lorenz Vetter, total production of forged heavy frame SIG P210 pistols added up to 278 as follows.
Serial Numbers Configuration Production Date
P58931-P58940 P210-5 National Match in 7.65 Para March 1966 for SMSV
P60431-P60448 P210-5 National Match in 7.65 Para January 1969 for SMSV
P79101-P79150 P210-6 National Match frame, marked “SWISS MADE” for Hofmann & Reinhart; 25 in 7.65 Para followed by 25 in 9mm Para; military sights March 1975
P76521-P76620 P210-6 with micrometer sights in 9mm Para May-June 1979
P79621-P79720 P210-6 with micrometer sights in 9mm Para Through the end of 1979

SIG P210-6 9mm Para forged heavy frame pistols, serial numbers P79608 and P79609, in a French-fitted case by Marvin Huey.
Test target dated 23 February 1978.

Concluded here.


Erwin Armbruster & Werner Kessler, Begegnungen mit einer Legende — SIG SP 47/8 / P 210, Kessler Waffen AG, 2007

H.P. Doebeli, Die SIG Pistolen, Motorbuch Verlag, 1981, ISBN 3-87943-739-4

Robert R. Field, “SIG P210-5 Heavy Frame: Präzise Rarität”, Deutsches Waffen-Journal, Februar 1992, pp. 192-197

“Porträt von Léon Crottet”, «SchiessenSchweiz», dem offiziellen Verbandsorgan des Schweizer Schiesssportverbandes, Dezember 2012, pp. 54-55

Lorenz Vetter, Das grosse Buch der SIG-Pistolen, Motorbuch Verlag/Verlag Stocker-Schmid, 1995, ISBN 3-7276-7123-8

“Waffengeschichte: Léon Crottet und seine Weiterentwicklung der SIG P 210-8”, Schweizer Waffen-Magazin, Januar 2015

— The author thanks Klaus Brunnemann for his contributions of the DWJ issue referenced above.

Tags: german, guns, p210, research, sig, swiss

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