June 2001:

The Colt Model 1900 Automatic Pistol
Colt Model 1900
Type:  Self Loading Pistol
System of Operation:  Recoil, "parallel ruler"
Caliber:  .38 ACP
Capacity:  7 round box magazine
Sights front: Blade 
Sights, rear:  Notch
Length: 9" l
Weight (loaded): 35 ozs
Barrel: 6"

The Colt Government Model design, fifteen years in the making, would later be manufactured under license in five countries, copied in more than a dozen, and universally recognized, from the high plains of Argentina, to the jungles of the Philippines to the Russian steppe.  Indeed, to many, it is the operating definition of the word "pistol," and the first image conjured when the word is spoken.  It was not, however created in a vacuum.  Behind the Government Model were an entire series of recoil operated pistols designed by John Moses Browning that used what is known as the "parallel ruler" locking system.  Manufactured to extremely high standards, and using the finest materials, these older Colt automatics have a smoothness and an elegance all but unknown today.  Indeed, they are considered by many to reflect a higher form of the gunmaker's blend of art and science than the Government Model that made them obsolete overnight.  It is one of history's small ironies that these developmentally critical pistols are all but forgotten today because of the Government Model's success.

John Browning's association with Colt's Patent  Firearms Manufacturing Company began late in 1890, when Browning and his brother, Matthew had presented Colt's with a design for a machinegun.  Fortunately for handgun development, Colt's took their time about producing a machinegun from the design (which later became known as the Colt Model of 1895, aka "Potato Digger").  In the interim, Browning applied his talents to applying the operating principle of the machinegun design to a magazine pistol.  The prototype pistol was
Browning Prototype Magazine Pistol
Browning Prototype Magazine Pistol
demonstrated to Colt's management on July 3, 1895.  Essentially a "blowback" design, it incorporated a gas port in the top of the barrel approximately one third of the way back from the muzzle, and a vertically pivoting arm at the front of what would now be considered the "slide."  When the arm is fired, a portion of the propellant gas is tapped off at the port and diverted upward.  As it moves up, it strikes the pivoting arm, which reacts by swinging up and to the rear.  This motion in turn causes the slide to move rearward, effecting extraction and ejection.  The pistol is then returned to battery, stripping a new cartridge into the chamber by action of the recoil spring.  While an idiosyncratic design, it opened 
many new doors for Colt and Browning, and military and commercial circles were abuzz with speculation that it was only a matter of time before the self loader completely supplant the revolver.

Six months later, John Browning returned with the design for a blowback pistol that eventually became the FN Browning Model of 1900 and establish Browning as the world's pre-eminent designer of self loading pistols.  1896 was to be a banner year for him, yielding most if not all of his major patents.  Between January and June, Browning journeyed from his Ogden, Utah home to Hartford several times, each time bringing a new prototype with him.  Following the blowback design were the two Parallel Ruler prototypes that were to dominate the large bore self loading pistol market in the United States for the next fifteen years.
The phrase "Parallel Ruler" describes Browning's original recoil operation locking mechanism.  In this design, the barrel is attached to the frame with two equal length links, one at the front and one at the rear.  Upon firing, the slide and barrel move to the rear together, locked by interlocking lugs at the top of the chamber and the underside of the roof of the slide.  As the rearward movement continues. the links rotate rearward and draw the barrel down, parallel to the frame.  This downward motion
pulls the barrel out of 
Parallel Ruler Locking System Patent Drawing
engagement with the slide, which is then free to move to the rear, completing the firing cycle.  The slide is retained on the frame by a transversely mounted locking bar which is held in place by pressure from the recoil spring.

Browning's .38 Caliber Prototype of 1897
Browning's 1897 Prototype, .38 Caliber
Browning refined his original prototype in the winter of 1896 - 1897 adding a rear sight that incorporated a safety system.  The safety has a notch milled into it parallel to the axis of the bore that serves as the rear sight when in the raised position.  When lowered, it serves to lock the firing pin, rendering the pistol safe.  The magazine was secured by a heel clip arrangement.  The 1897 prototype was chambered for the .38 ACP cartridge.  With the successful testing of the prototype, Colt's had its Model Room produce a pilot series of the pistol, also chambered for the .38 ACP cartridge.  One of these, serial number 02, was tested by a US Army Board of Officers in November 1898.
On October 19, 1898, Colt's had been informed by US Army Chief of Ordnance Daniel W. Flagler that a board was to be convened to test available revolvers as possible new service arms for the US cavalry.  Taking advantage of the opportunity to gauge military reaction to the automatic pistol design, Colt's submitted pilot series pistol 02.  No doubt contributing to Colt's inclination to send a pistol to the trials was the knowledge that Mauser, Mannlicher, Borchardt, and Bergmann designs would also be submitted.  The Board, consisting of four officers (three cavalrymen and an ordnance officer), arrived at Colt's on Friday, November 11, 1898, and tested the automatic pistol and four Colt revolvers.  Interestingly, the reason behind the board seems to have had more to do with the debate between the proponents of small caliber high velocity firearms and those of the slower, heavier .45 caliber guns.   Given this, the board's interest in the automatic is all the more remarkable.  A portion of the official report reads:
The Board is of the opinion, based on a careful examination of the Borchardt, the Mannlicher, the Mauser, the Colt, and the Bergmann repeating weapons that the development of this type of pistol has not yet reached such a stage as to justify its adoption in place of the revolver for service use.
The use of the word yet strongly implies that the board was of the opinion that the replacement of the revolver by the automatic was inevitable.  Of course, they had some help in that determination.  As a product of Colt's Model Room, the automatic tested was of the very highest quality and workmanship.  Fit and finish were excellent, and grips made of the highest quality walnut.
Colt's 1898 Army Test Pistol
Colt Army Test Pistol of 1898
Model of 1900
While Colt was getting ready to go into series production of the Browning automatic, another test was conducted by the military at Springfield Armory in February 1900.  The competing pistols included a Mauser C96 and a Mannlicher as well as the Colt.  All of the entrants were subjected to the most severe testing.  The pistols were disassembled and reassembled for time.  They were fired for accuracy and penetration.  They were subjected to extended firing tests to determine endurance and reliability.  They were subjected to sand, and then rusted in a solution of sal-ammoniac.  When it was over, the Mauser was a solid mass of rust.  The board had found it well made, but bulky, awkward, overly complex and expensive.  The Mannlicher had been withdrawn from the tests when its barrel burst after 336 rounds.  In contrast, the Colt's entry had great appeal for the board, as a comment made at the conclusion of the tests indicated:
. . .the test to which this pistol was subjected was in every way more more severe than that to which revolvers have been heretofore subjected, and the endurance of this pistol appears to be greater than that of the service revolver.
Colt's 1900 Army Test Pistol
Colt Army Test Pistol of 1900
Indeed, some 4,500 rounds were fired through the test pistol after the rust test, the only failures were in the barrel links, which were easily replaced.  In the end, the board ran out of ammunition before it could wear out the gun.

As a result of the test, the board recommended that a number of Model 1900 pistols be purchased for field trials.  Fifty of these were sent to the Philippines, where they received rigorous testing and nearly unanimous praise.  As reports came in, shortcomings were identified and improvements suggested.  Among the shortcomings noted were:

In a surprising display of corporate flexibility, Colt's and John Browning ensured that all these improvements were later incorporated into the gun.  Despite the shortcomings, some 200 officers in the Philippines made official requests for the pistol.

While the military tests were being conducted, Colt's was not ignoring the commercial market.  On February 14, 1900, production serial number one was shipped to A.C. Gould of Shooting and Fishing magazine.  Shooting and Fishing featured the pistol in the April 1900 issue, and commented "We do not hesitate to go on record as stating that arms of this type will supersede the revolver."  Early commercial Model 1900's are elegantly simple in appearance.  All had the notch at the rear for the sight safety, although many were later converted to use a fixed rear sight.  Smooth wooden grips were supplied up to serial number 2449, at which time checkered hard rubber "scales" became standard.  Cocking serrations were a series of sixteen vertical plunge milled grooves at the rear of the slide until approximately December 1900, when they were moved toward the muzzle end of the slide.  Fit and finish were uniformly excellent.

The Navy was quick to follow the Army lead with respect to the Colt's autoloaders, taking delivery of some 250 Model 1900 pistols in the latter part of 1900 to test their suitability for fleet usage.  Navy pistols bore idiosyncratic markings consisting of a trident shaped acceptance stamping on the right side of the trigger guard webbing for all but the last fifty trials pistols delivered, which had a star shaped acceptance stamp.  All of the Navy pistols bore the Colt's factory serial number on the right side of the frame above the trigger, and the Navy property number on the left side of the frame above the trigger.  All 250 Navy pistols have a tiny letter B inside a triangle on the left side of the triggerguard webbing.

With the ink on the critique of the pistols from the initial Army tests barely dry, a second Army order was placed for 200 pistols in the fall of 1900.  This second batch of Army pistols incorporated some of the changes requested by the officers in the Philippines.  The grips were enlarged and checkered, and the cocking serrations moved forward so as to prevent the cocking hand's interference with the sight safety.  Markings on the second Army contract include "US" stamped on the left triggerguard webbing, and the initials of inspector Rinaldo A. Carr (RAC) on the right.  While the improvements in the second Army contract pistols did little to advance the pistol technically, they served an important political purpose, 
Colt Model 1900 Second Army Contract Pistol
Colt Second Army Contract Pistol
cementing the relationship between Colt's and the US Army Ordnance personnel who would be judging the new service pistol competition that would take place a few years later.

Commercial production, as always, was kept abreast of the military modifications.  Around serial number 2460, rounded hammers began to replace the spur hammer on Model 1900's and in December of 1901 the sight safety was replaced with a fixed rear sight.  Remaining stocks of slides cut for the sight safety were converted by milling a dovetail for the new fixed sight and inserting a carefully milled insert into the top rear of the slide.  The original steel firing pins were exchanged for ones made of bronze.

Colt Model 1900 Sight Conversion
Colt Model 1900 Sight Conversion Pistol
In early 1902 a takedown device was incorporated into the pistol. Original Model 1900 takedown procedures required a pin, approximately the diameter of a paperclip, to be inserted into a hole on the bottom of the frame with the slide drawn to the rear approximately half an inch.  With the pin so inserted, the forward motion of the recoil spring was blocked. Tension on the slide lock was then relieved, and it could be pushed out to the left, and the slide pulled to the rear and off the frame.  The 1902 improvement consisted of a takedown plug beneath the barrel at the muzzle end.  Putting a slight pressure on the plug allowed the slide lock to be removed.  Earlier and later takedown systems can be identified by the 
shape of the plug beneath the muzzle - takedown plugs are concave while the fixed plugs are convex.

Interestingly for the collector, converted pistols are often seen in serial number sequences subsequent to those manufactured with the new features.  This was because of Colt's' practice of using up stocks of obsolete parts in the most economical manner - which was to sell them as part of new guns!

Perhaps the most technically daunting of the criticisms of the Model 1900 was that it took too long, and required two hands to bring the gun to a ready state.  In comparison, revolvers could be unholstered and brought quickly into action with one hand.  Browning elected to solve the problem in pieces.  Reasoning that once the pistol was in action, reloading could be made easier by incorporating a mechanism that would hold the slide to the rear once the last shot in the magazine had been fired.  This way the shooter needed only to replace the empty magazine with a full one, and release the slide to chamber a fresh round.  After working out the design, Browning incorporated the mechanism into a Model 1900 
Browning Slide Lock Prototype
Browning Slide Lock Prototype
pistol that happened to be at the Browning Brothers' shop in Ogden.  The mechanism was simple.  A notch was cut into the left side of the slide, and a sliding bar was dovetailed into the left side of the frame behind the trigger.  When the last round was fired, the magazine follower placed upward tension on the bar, which engaged the notch in the slide as it  traveled rearward.  A finger tab was incorporated into the stop bar to enable the shooter to easily release the slide.  Browning was granted patent number 708,794 for this invention on September 9, 1902.
Colt Military Model of 1902
Colt Military Model of 1902
In response to further Army Ordnance suggestions for improvements, Colt's further modified the Model 1900 to incorporate the improvements.  These included lengthening the frame and squaring it off, adding a lanyard ring to the left side of the frame, and discarding the plunge milled vertical slide serrations in favor of fine checkering.  With these improvements, the pistol ceased to be the Model of 1900, and the Military Model of 1902 was born.
The "parallel ruler" Colts in general, and the Model 1900 in particular, are often overlooked and cast in the shadow of the Model 1911.  As a result, we suffer from a distortion in historic perspective, the extent of which is magnified when it is remembered that the Model of 1911 broke very little new ground, being an evolutionary development of the arms that came before it.  Browning's prototypes and the Model 1900 were the truly revolutionary guns for their time whose design features still dominate handgun technology today.  The Model 1900's design is the direct progenitor of most of the world's successful autoloading pistols; it's hard to pick up a self loading pistol that doesn't exploit features first encountered on the Model 1900.  They were superbly made and finished firearms that took on the best designs in the world, and won.  Indeed, there is ample merit to the proposition that the true monument to John Browning's vision and genius is not the phenomenally prolific M1911 style pistol, but the M1900, which made it all possible.


Goddard, William H.D., The Government Models, (Andrew Mowbray Incorporated, Lincoln, Rhode Island:  1998)

The Government Models is available from IDSA Books.  Click on the image to order:
The Government Models by William H.D. Goddard

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