Colt M1900

The Colt Model 1900 was a self-loading semi-automatic .38 caliber handgun introduced by Colt at the turn of the 20th century. It also marked the introduction of .38 ACP, the round for which it is chambered (not to be confused with the smaller .380 ACP).

It was developed from John M. Browning's earlier prototypes in the late 1890s. The United States military tested the design against other semiautomatic pistols by European makers, and adopted some versions for trial use. The M1900 and variants were also offered commercially. Variations included the Model 1902 Sporting, Model 1902 Military, Model 1903 Pocket (in .38 ACP; the .32 ACP model was a different design), and the Model 1905, which introduced the .45 ACP cartridge. The designs of 1909 and later did away with the front bushing, and would become the M1911 pistol.

Design
Unlike the designs of other early automatic pistols, Browning's design used a full length slide that covered the full length of the barrel, as opposed to other designs which utilized a barrel and bolt that slid into grooves in the frame. In the Browning design, the slide fitted into rails in the frame, and the barrel rode in tilting links secured to the frame, one at the front and one at the rear. When the slide was forward, the links lifted the barrel up, locking it securely into matching grooves in the frame. Upon recoiling, the barrel moved backwards a short distance, then the links pulled the barrel downwards, disengaging it from the slide. The barrel then stopped moving, while the slide continued rearwards, extracting and ejecting the fired cartridge case and loading a fresh cartridge from the magazine.

The new design also featured a new cartridge, the .38 Automatic Colt Pistol. Despite the name, this cartridge used a .357 caliber bullet weighing 107 grains, at a velocity of 1259 ft/s. This was a larger caliber than other contemporary designs, which were predominantly 7.6 mm, or .308 caliber, at similar velocities. The .38 ACP was also much faster than the .38 Long Colt revolver cartridge in service at the time, which fired a 130 grain bullet at 770 ft/s. Colt was also experimenting with a .41 caliber cartridge for use in the Model 1900, as reported to the Ordnance Department during testing. Like the .41 Long Colt, this probably used a .400 inch bullet. The poor performance of the .38 Long Colt in combat in the Philippine-American War of 1899–1902 resulted in the re-adoption of the .45 Colt, and eventually led the War Department to specify a minimum caliber of .45 for the new handgun. The prototype .41 caliber Colt automatic cartridge was never produced in production quantity, but the concept anticipated the development of the .40 S&W by over 90 years. Colt did produce a few "Model 1903" .41 cal. pistols, conversions of Model 1902 Military Models (the 1902 Military was an improved M1900/02), for the cartridge before the development of the cartridge ended.

One of the .41 pistols is on display in the Connecticut State Library, Hartford, CT. The most prominent feature of the Model 1900 was the sight safety, which while a good idea in theory, did not work out well in execution, and proved to be unpopular. When pushed down the safety blocked the firing pin, when pushed up it performed as the rear sight. The first 1900s were equipped with rear milled slide grooves but when it was found that this could interfere with the sight safety the milled slide grooves were moved to the front. This safety was used in about the first 3,000 production pistols. Colt then installed a conventional rear sight and eliminated the sight safety although the cut in the slide remained but was plugged. The grooves, remained in the front of the slide. There are earlier sight safety M1900s that were factory retrofitted with the new fixed sight. Although Colt considered a new firing pin safety mounted on the left side of the slide with one prototype, it did not produce such a model. This was possibly a mistake as the lack of safety features probably affected sales – the recommended way to carry a no safety Colt automatic was with an empty chamber which made it slower to get in action and required two hands – a major complaint of the military which tested it, something Colt was for some reason loath to fix in the 1900–1902-1903 series of pistols. The only exception was the new 1903 pocket hammerless, a completely new design with a grip and frame thumb safety at the start of production in 1904. It is possible that Colt found it cheaper to introduce the features into a new model, and the sales of the 1903 hammerless were spectacular in comparison to the 1900/1902/1903 large frame automatics. By contrast, Mauser C96's and Lugers had manual thumb safeties from the outset.

The Model 1900s were initially fitted with distinctive "high" spur hammers until approximately serial 2400 when "stub" rounded hammers also began to appear. As approximately 1,450 of the M1900 "high" hammers were left over when the M1900 merged into the M1902 sporting model, (the 1902 sporting model being a continuation with some internal modifications of the M1900) starting at serial 4275, it might be surmised that perhaps approximately 3,000 "high" hammer (mostly early) and about 1274 "stub" hammer M1900s were produced. Stub hammers may also possibly show up in some retrofitted earlier pistols. Numbers at this time can only be considered approximate. Collectors need to continue to post and communicate observations of surviving pistols.

US War Department testing
The United States War Department solicited designs of semiautomatic pistols in 1899, and chose three samples to test; the recoil operated Mauser C96 "Broomhandle", the unusual blow-forward action Steyr Mannlicher M1894, the Browning designed Colt, which was not ready until after testing started. Testing consisted of accuracy, penetration, and reliability tests, ergonomics testing, and torture tests. Ergonomics were considered very important, as the pistol was intended for use by cavalry, which meant it had to be readily operated and reloaded from horseback. Torture tests included a dust chamber and a rust test.

Mauser C96
The Mauser was the first sample tested, as the Colt was not ready, and the Mannlicher representative was unreachable when testing started. The Mauser worked reasonably well in initial testing, with nine misfires caused by a failure to return to battery, one failure to eject, two failures to chamber, and a broken extractor. The dust chamber test resulted in six of ten rounds failing to fire on the first attempt, and one failure to chamber. The Mauser failed miserably in the rust test; the mainspring rusted into pieces, and the gun required soaking in oil for several hours before it could be disassembled with the use of a mallet. After a cleaning, oiling, and repair, the pistol was tested again, and experienced a number of failures to feed caused by cartridges sticking in the clip.

Colt M1900
The Colt was tested next, as the Mannlicher sample had still not been received from the manufacturer's representative. Testing began in February 1900. The Colt had a number of initial problems, due to ill fitting parts in the trigger mechanism, which eventually required the attention of a manufacturer's representative, who fitted a new trigger mechanism. Once this was done, the pistol fired the remaining 293 rounds of the 500 allotted for the endurance test, plus an additional 150 rounds with no malfunctions. Another supply of ammunition, consisting of 350 rounds of low velocity .38 ACP ammunition (935 ft/s) was also tested, with no adjustments to the recoil spring. This was done to test the repaired trigger mechanism, and while it was not expected to function with the pistol tuned for the 1200 ft/s ammunition, only four failures were experienced with this ammunition. The pistol fired all ten rounds with no malfunctions during the dust test. After accelerated rusting with sal ammoniac, the pistol was frozen so that the slide would not move. A sharp blow on the edge of a table with the slide freed it enough to allow the slide to operate, and a round to be chambered. After firing the first round, the slide failed to return to battery, but was readily closed, and the remaining rounds functioned without malfunction. All remaining ammunition, 23 rounds, was then fired through the rusted gun with no malfunction.

Mannlicher 1894
The Mannlicher pistol was the last tested. The Mannlicher, unlike the Mauser and Colt, used a blow-forward action, where the barrel was pulled forward on the frame by the friction of the bullet in the bore. Since there is no rearward moving bolt or slide to cock the hammer, the pistol used a double action trigger, rather than the single action triggers used in the recoil operated guns. The pistol experienced a number of failures to fire; it was noted that the barrel did not always return to battery, and most failures to fire were corrected with a second pull of the trigger. On the 281st shot of the 500 round endurance test, cartridge and barrel both burst. Due to ergonomic problems with the pistol, it was decided to terminate testing at that point.

Further testing of the M1900
The Colt performed well enough during the first round of testing that the board subjected it to additional endurance testing. A 900 round trial resulted in only two failures, both misfires due to defective primers. Additional ammunition was procured, and testing continued. During this testing, a number of link pins were also broken, and in one case continued firing with a broken rear link caused the barrel to separate just behind the front link pin. After firing a total of 5,800 rounds through the pistol, the only significant problem found was the weakness of the link pins, which was considered readily fixed by the ordnance board. The board recommended purchasing a number of the Model 1900 Colt pistols for use in field trials.

Production
A number of variations of the Model 1900 were produced during 1900–1923.
 * Model 1900. Six inch (152 mm)  barrel, walnut or hard rubber grips, high spur hammer, sight safety.  Produced 1900–1903.
 * Model 1902 Sporting. Hard rubber grips, no safety, round or high spur hammer.  Produced 1902–1908.
 * Model 1902 Military. Similar to 1902 Sporting, but adds a lanyard swivel on bottom rear of left grip.  Produced 1902–1929.
 * Model 1903 Pocket. Similar to 1902 Sporting, but with 3¾ or 4½ inch barrel.  Produced 1903–1929.
 * Model 1905. Similar to 1902, but with a 4⅞ inch barrel, and chambered in the new .45 ACP.