Colt/Browning Sight Safety 1900

In 1897, John Browning patented four different types of automatic pistol – a blowback type that would become the FN/Browning 1900, a gas-operated type similar in concept to his 1895 machine gun, a rotating-barrel type, and a swinging-barrel type. It is this swinging barrel design that would have the most lasting impression. In 1898 a sample of this pistol – manufactured by the prestigious Colt company – was provided to a US Army ordnance board to be tested alongside other early semiauto pistols (including the Mauser C96 and the Mannlicher 1894 blow-forward). After some improvements, the gun went back to the ordnance board in 1899 for a more extensive test, which would ultimately see 5,800 rounds fired through the gun with minimal problems. In light of this, the Ordnance Department purchased 100 of these pistols for more extensive testing in 1900.

The pistol was never formally designated the M1900, although that is the name usually used to describe it. Colt simply called it the Colt Automatic Pistol, as it was the first such design they had produced. Unlike the eventual 1911 design, this early gun used two swinging links on the barrel, one at the muzzle and one at the chamber. This meant that the barrel remained parallel to the slide at all times, rather than tilting in a front bushing. The 1900 model was chambered for the .38ACP cartridge (also designed by Browning), which was used because the standard Army handgun cartridge at the time was a .38 caliber revolver cartridge. Browning’s early prototype of the gun actually used standard rimmed revolver cartridges, but he designed the rimless .38 ACP to improve reliability in the self-loading action.

The colloquial name of this pistol – the “sight safety” comes from the location of the only external safety on the gun, which took the form of the rear sight. The sight was mounted on a pin, and could pivot up and down. When snapped down (only a few millimeters down from its normal firing position), the rear sight physically blocked the hammer from contacting the firing pin. It was a very simple mechanism; not interacting with the fire-control parts at all and not preventing the slide form moving when engaged (actually, is was very similar in practical terms to the safety on the later 1905 Steyr-Mannlicher pistol).

This safety was one of the weak point of the gun. It was not easy for the novice to tell if the safety was engaged or not, and it was impossible to operate with the firing hand. Worse, it was small, and generally tricky to operate in any sort of field conditions (when wet, with gloves, etc). It was widely criticized by Army officers testing the guns, and was dropped in fairly short order, leaving later model 1900 pistols (and the follow-up 1902 model) with no mechanical safety.


  1. I assume this development is what drove Browning to create the thumb-operated safety seen on 1911’s and other Browning-action pistols. Otherwise someone would shoot Marvin in the face or get killed when the safety was bashed.

  2. The original cartridge the 38acp was less powerful than the modern 38 super although dimensionally the same. The modern cartridge 38 super should not be fired in the 1900. The rear sight when down gives no sight picture and thus indicates when on. The twin link technically gives better accuracy. One of the early Webley automatic pistol prototypes used a derivation of the twin link.

    • …and the terminology “parallel ruler locking system”.

      I was amused by the commentator on the old “Tales of the Gun” show who explained the term as meaning “highly accurate”, as opposed to being a direct reference to “parallel rulers”, the drawing instrument which operate in a similar fashion.

        • Same mechanical concept, with the inclusion of an actual recoil mechanism.

          When the gun is fired, it recoils back and down against the recoil mechanism, whereupon it’s held in place until the piece is reloaded and released into battery. I don’t have my Servin handy, so I can’t recall which models had a slide stop, and whether an empty magazine activated it. Assuming it did on the ones which had one, the disappearing gun works like a dual link Colt with one round in the magazine.

  3. I like this pistol. And I know that I’m not supposed to post this here, but my girlfriend broke up with me yesterday and u really have nowhere else to talk about it. I’m 17, a junior in highschool. I always got picked on because I’m weird and girls never really liked me. This year, I had my first girlfriend and I never really felt like someone has cared before then and now she broke up with me. I really don’t wanna go back to being bullied again. I always get called a terrorist because I like guns too, anyways can anybody help?

    • As a fellow enthusiast who graduated from college last year, I would advise you to keep any conversations with others towards something a little less explosive (in the social-political sense, as well as what we are discussing). I know how it feels to get bullied and called “terrorist.” First, try not to view yourself as weird. Next, ask yourself if it is wise to try getting a girlfriend in your current state. I know you want to have good relationships, but please don’t place your social status among your peers above your need to survive once you graduate. I’ve had to give up getting a girlfriend so I could go to a very prestigious university in Cleveland (I’m not telling the name so nobody can steal my ID and make a good impersonation of me). Over there, course-work intensity will interfere with any romantic ties, especially during senior semesters.

      I know being bullied is unpleasant, but the bully will not rule your life. I doubt bullies will actually be able to survive once out of high school, since they will not likely know how to survive college.

  4. I love the early Colt pistols and revolvers, especially the M1900 and the M1902. Partly because i am a fan of .38 Caliber ammunition (Am i the only one to prefer .38 Caliber over .45 Caliber, the latter seems to have been the favorite ever since introduction), and partly because i like older pistol designs more than those with a more modern look. I have long waited someone to give a gopd explanation of the sight safety, so this video was a pleasant surprise. I hope to one day get a Colt M1902, which i prefer over this one, but i don’t know if one would ever encounter such a rare weapon outside of the USA.

    Great video though, and a good choice of gun.

    • .45 is fine, but I prefer .38/9mm for the most part myself. More pleasant to shoot, for one thing. But I guess I’m in the minority among American shooters.

      • In Europe the 9mm bullet (not only Luger – don’t forget Austrian 9x23mm Steyr and Spanish 9x23mm Largo) was/is prefer over bigger bullet in automatic pistols. Prior to the WWII the .45 caliber was so far I know used in service automatic pistol only in Great Britain (Webley & Scott .455 Mark I Navy pistol) and Norway (Kongsberg Colt – license version of Colt 1911).

        • Like I said before, there is absolutely nothing wrong with the 9/38! You missed the point of my reply, I think? When the 9/38 is loaded to less recoil than the typical .45, it is just less of everything. Nothing more, nothing less. When it is loaded to equal the .45, it also has more recoil than a .45! It is impossible to get more of anything for less of something. You make your choice and take your chances. That is all there is to it.
          I guess it boils down to the old argument; Which would you rather have in a close range gun fight? A .22 LR Pistol, or a 12 Gage automatic shotgun? The difference between 9/38 and .45 are points on that continuous line.

      • This is part of the great fallacy! 9/38 is only more pleasant to shoot when it is loaded to inferior ballistics to the larger caliber. For instance; 9 mm NATO is a 124 grain/8 gram bullet at 1295FPS/395M/S, for >620J/466FPE! This load absolutely has more recoil bite than the typical .45 load and it is in a weapon that is harder to shoot as well. (6.25J of recoil energy in a Berretta and 8.5 grains of fast propellant with almost 9,000 PSI of muzzle blast for the NATO load and 7.1J with 5.5 grains of well under 5,000 PSI muzzle blast for the .45) The difference in actual recoil is about 14%, but the difference in muzzle blast is 278% higher with the 9/38. Now we load the nine/38 down to 1150 FPS with a 115 grain slug and recoil in a much lighter Glock is 5.3J with about 5.5 grains of fast powder and 8000 PSI of muzzle blast. The Nine and most .38 auto cartridges are high pressure and they do not cycle the action when loaded down. The full size .45 on the other hand, cycles well with a 155 grain slug at 750 FPS, for only 2.6J of recoil and about 9% as much muzzle blast! All of these things count!
        There is a great deal of misconception out there. If you are in the state line area between Beloit and Rockford any Wednesday morning, call me to bring it all up, come by the club and be my guest. I have ALL of those toys to shoot and all of the appropriate ammo to prove my points. Choose between six, or seven different 9s and 7-8 .45s along with larger and smaller guns. Would you believe that a “Baby” Browning .25 has more recoil than a full size .45 shooting the above softball loads? learn the truth. There are to many variables to make EASY CHOICES, or blanket statements like you do above!

    • Hi; Acceptance of .38/9mm ammo is wide spread and well deserved. It is certainly lethal if struck in the right place. The problem is and always has been two fold.
      First getting hits at all is nearly impossible under combat conditions in the real world regardless of caliber! This is a fact that is beyond dispute and not open to debate. .38/9mm helps this in some respects in some pistols when it’s load has less recoil than a similar .45.
      Secondly, once you got a hit, it was not always in the right place. While the difference between .38 and .45 at .095″ does not seem like much, that difference is 60.3% more soft stuff damaged buy the larger bullet. in addition, the larger slug is less likely to shoot through as in “Through and through” and thus waste much of it’s energy down range making the difference even more pronounced.
      The introduction of deforming bullets, read JHP, for automatic pistols helps the smaller caliber some, but that initial 60% only gets worse when the same type of ammo is used in a .45!
      These two points are born out by the willing ness over the last 125 years or so by the desire of most National Armies and Police Forces to use the smaller less effective rounds world wide. It is easier to learn to shoot guns with less recoil. Also the huge and intransient reluctance of those two Armies which were required to deal with LIPs, who did not have the common courtesy to lay down and die when struck with minor caliber rounds, to adopt the smaller caliber rounds. IE the Americans and British Armies which stayed with .45 caliber ammo. They knew these facts and wanted more “Stopping power”!
      While I “know” that stopping power is mostly a myth, or “Urban legend”, I also know that a poorly placed shot is much more likely to be effective, buy whatever term you use to measure that, if it is a larger caliber.
      Then comes the next to last tid-bit. most guns chambered for the .38/9mm have “double action/single action” triggers and are thus a very much harder weapon to train to any given standard. IE it is very much easier to train to shoot a 97/100 with a single action only pistol than with any of the modern “Wonder nines” and why Army trainees scores with the 1911 were better than they are with the M-9.
      Lastly, To make the 9mm and the .38 more effective, it is loaded to much higher pressure to generate more Muzzle Energy. This generates much more recoil and makes it even harder to train raw recruits how to shoot well, and shooting well is many times more effective than shooting bigger bullets with more energy!

      • The main problem with stopping power is that the stopping power is considered as a magical force which can solved all problems.
        It is certain that slug from 12 gauge which miss target is as effective as .22 bullet which miss target.
        It is crucial to understand that stopping power is simply number assigned to particular cartridge.

        The second problem with stopping power is that TKO formula is used to describe handgun rounds, despite it was designed for African rifles which uses rounds with heavy and slow bullets. The handgun rounds efficiency can be better evaluated with Hatcher’s formula (Hatcher’s RSE factor, RSE=Relative Stopping Energy).

        • I used to believe in the Hatcher formula, but I’ve come to the conclusion that kinetic energy (KE) is really the only index of “stopping power”.

          Simply put, it takes about 250 FPE (340J) of KE to inflict a debilitating or lethal wound on an average adult male human. Which is why the Red Army designed the 7.62 x 39mm round to have at least that much retained energy at 400 meters. (This is also about the muzzle energy of a .38 Special 158-grain RNL “police load”.)

          The U.S. Army determined after WW2 that the .45 ACP, 9 x 19mm, and 7.62 x 25mm all got about the same results in terms of “one-shot stops”- about 65 to 70 %. All three delivered about 325 to 350 FPE (440-475J) to the target at close range. In spite of doing it three different ways; big,slow bullet, medium-sized, medium-velocity bullet, and small, really fast bullet.

          The math pretty much say it all.



          • I have a hard copy of the “Army Report” about the 3.9 million wounds that they studied, and I can not find any place where it states those things! If anything, it states the exact opposite. (IE, that the larger the missile, the more likely it was to kill or incapacitate!)
            In the study you “quoted” they found that all handguns had the same effectiveness.
            But my time in the Army taught me the opposite. It is nearly impossible to teach army recruits to shoot 7.62X25 hand guns to the same standard as other hand guns because of two factors. High recoil and higher muzzle blast. 9mm Handguns are next hardest to train up to any standard for the same reasons and .45s are the easiest weapons to bring the average recruit to the point where half his or her rounds hit the target at 25 yards.

          • Stewart;

            I was going by Marshall’s Handgun Stopping Power, plus various articles in Handguns magazine.

            If that is incorrect, I do apologize.

            I think “stopping power” is a very subjective subject that has engendered a lot of emotion, and I normally try to stay out of such debates.

            That said, 300-350 FPE impacting on a mass should have about the same effect, regardless of how it “gets there”. “Gross” physics is pretty clear on that point.




        • Valid points, EACH in their own way. But most modern, or current readers believe that Dr. Martin Flacker is the world’s pre-eminent expert on wound ballistics. He thinks that little beyond the damage track is effective from typical handgun ammo.
          After WW-II, the US Army studied 3.9 million wounds and came to the conclusion that LESS than 80 Joules is all that is required to cause a debilitating, or fatal wound! It all depends on where it hits and what organs are damaged. More people in America are killed each year by .22 Long Rifle ammo than any other type. It’s just statistics. more shootings = more fatalities.
          But that is not the point of a Defensive Service pistol! A weapon to protect yourself and loved ones must be effective in the shortest possible time. It takes the typical bad guy between 15 and 30 seconds to bleed out and collapse from a T&T heart shot. The COMPLETE loss of blood pressure leaves about 15 seconds of mental action available to the perp. During that time he can run 100 yards and kill a dozen people.

          To damage tissue requires kinetic energy. The energy density, IE energy per unit of frontal area of the smaller hand gun bullets is typically much higher than for larger caliber ammo. That means that it penetrates deeper, but with a smaller hole.
          If 10″ equates to a Through and through all other penetration is wasted, then 9X9X254 MM is proportional to the damage track. (Score 20,574!) JHP bullets tend to expand and 15 MM is typical, then the equation becomes 15X15X254=57,150!)
          A .45 ball is 11.5X11.5X254=33,591.5 or about 163.3% more damage! A .45 JHP is 20.3X20.3X254=104,670! ( Nearly twice as much damage as the smaller JHP round!)
          There is no possible way to overcome these facts. Bigger hole are better than smaller holes when it comes to saving lives.

          • The Hollow-Points are certainly more effective than their FMJ counterparts, but remember that use of “bullets which expand or flatten easily in the human body” by Armies and Navies is prohibited due to Hague Convention of 1899. So, when you must use the FMJ, but you want more effectiveness the heavier and/or faster bullets is clear way to do that.

  5. Not to quibble, but I thought all the Browning cartridges prior to the .380 ACP (introduced 1908)were semi-rimmed rather than rimless.

    Ezell lists the .38 Auto Colt introduced in 1900 as the 9 x 23mm SR, and states that

    The designation .38 ACP is not to be confused with the .380 ACP designation of the 9 x 17mm Browning Short cartridge; the two rounds are quite different. The 9 x 23mm SR was not developed as a metric cartridge; it was introduced in 1900 by Colt for their Browning-designed .38 automatic pistol.

    -Ezell, Handguns of the World, p.686

    The fact that except for the semi-rim, the .38 ACP round is very close dimensionally to the 9 x 23mm Bergmann-Bayard Long aka 9mm Largo can cause problems. I once got a .38 Auto round firmly stuck in a 9 x 23mm Star Super A due to a mixup in loading the magazine from a carton of cartridges. Getting it out without making a mess of things was emphatically not fun.

    (Yes, I’d have kicked myself for such a dumb-boot mistake if my foot would have reached that high.)



  6. the 1900 sight safty is the rarestofthe colt automatics. Only 4274 pistols mad efrom february 1900 to mai 1902. most had the sight safty replacrd.
    nice book is printed in 1987 on the subjekt by Duglas GSheldon: Colts 38 automstic pistols.
    Mine are unalterd and has no. 2299 and were usedin the danish pistol tests in 1907

  7. These are very interesting pistols, and some of the first really practical combat semi-autos, along with the Broomhandle and Parabellum.

    I first got interested in them when as a child, I saw the movie “100 Rifles”, in which Fernando Lamas played a Huertista(?) Mexican Army officer who carried a matched set of M1903(?) Militaries (square butt and lanyard ring) with fancy ivory Mexican eagle grips. He uses them to execute Yaqui Indians, tied four or five together in a file, by shooting the first victim, the bullet passing through him and into the other 3-4. Given the tendency for over-penetration displayed by the 9x19mm FMJ, I suppose it’s not totally implausible, especially given the often higher muzzle velocities of factory ammunition in days gone by. I don’t guess they’d had enough time for the problem of crystalizing slide retention blocks giving up and launching the slide into the shooter’s face, to become a problem yet. That’s one reason why the slides on M1911s can only removed toward the front of the frame.

  8. Browning was a genius…and 40 years ago I started collection the 1911’s….which eventually led me into the “Colt Automatic” business. I did this for 35 years. The good lord blessed me with samples of Browning/Colt automatic pistols throughout those years. In 1986 I bought a 300 Colt automatic pistol collection. In the collection was, serial number 2 Colt 1900….sight safety, with the engraved slide legend, and a 1910 Special Army .45acp (looks like a 1911)…serial number 7, that was modified for the 1st thumb safety. This pistol also had the 360 degree locking lugs on the barrel. I eventually traded it on s/n 9 1909 .45acp automatic pistol. Over the years a had a quest for low numbered Colt auto’s and eventually ended up with s/n 1 1908 .380 automatic, s/n 1 Colt .22 Ace automatic, and many prototype Browning autos made for Colt. I had an early barrel bushing .32 automatic…in the white…no s/n and the engraved slide legend….like the 1900. The rarest of autos was the 9.8mm Bulgarian Colt 1910 test automatics. Bill Goddard had s/n 3…factory converted to .38acp (you can see it in his Government Model Book), I had s/n 1 & 4 that were in the original 9.8mm caliber, and 7/8 size of a standard 1911 (pictured in E. Scott Meadows book). A neat little pistol.
    Just as a note: I’ve had many of the 1907 trials .45acp Colt pistols….but the one that I always will remember….is one that I bought at the Los Angeles County Fairgrounds…at the Great Western Gunshow. I was perusing the tables early on a Sunday morning, and my girlfriend stopped at a table that had Indian and Western stuff/clothes. I notice an old patina’d Colt auto on the guys table…picked it up, and realized that it was a badly beaten up 1907 Colt test auto…the slide was cracked and brazed at the front locking bar…and the barrel was missing. There was a modified .38acp Colt Military Model magazine in it. And of course it had steer horn stocks. Virtually no finish….but not pitted. I bought it for $100….took it apart and found the link pins still in place…and attached to them was the barrel link-lugs. I couls see that they had been brass brazed to a barrel orinially. I have a feeling that someone had converted it to .38 Super….and blown the barrel out of it. Yeow! If that old pistol could talk!
    If I knew how to post some pictures….I’d be glad to do that.

      • Cartridge designations are frequently arbitrary at best. .38-40 Winchester is, if I recall, actually a .40.

        Sometimes they change, as in the case of the 7.92x57mm, going from .318 to .323.

        Sometimes, the “standard” isn’t. 7.62x54mmR and 7.62x39mm bores run all over the place, from .308 to .312.

        • Actually, there is more American rounds with “false” caliber than with true.
          .45-70 has .458 bullet, hence should be .46
          .30-06 has .308 bullet, hence should be .31
          .32 S&W Long has .312 bullet, hence should be .31
          and many, many more. These are old rounds but even nowadays new rounds with “false” caliber are crafted – for example
          .327 Federal has .312 bullet, hence should be .312
          Note that only one quite popular American rounds has 38 in name and it is true – the .38-55 Win (the exact bullet diameter is .3775 but when rounded to 2 digits it is .38)
          NEVER think that the same digits in round name always mean that the bullets diameters are identical – or you will destroy your firearms and wound yourself for example when you make .45 Long Colt with .45-90 bullets (as described here

      • I was pretty happy with how easy it was for me to read the Spanish.

        I just passed on a computer help desk job that required Spanish fluency.

        I wish I got more job opportunities requiring a knowledge of vintage firearms and Spanish…

    • WOW!
      I thought I was a “Collector”, but compared to you, I am a piker of the highest order!
      Have you taken the opportunity to test fire, or just shoot the hell out of any of those guns to really get a feel for them?
      Wish you the best of luck and profitability!

      • Even though I love shooting the .45 Colt 1911…and have shot 100,000’s of rounds at paper (in my 20’s I shot 500 rds a day)….shooting these “Mona Lisa’s” of firearms….would have been sacraligious. There are NO original parts to replace, if they break, and their history needs to be preserved. The only pistol I shot was a .45 Savage 1907 test pistol (using custom loaded ammo w/200gr lead bullets), and it kicked like a 2″ .44 Magnum. This pistol is a retarded blowback design and the shooter takes the abuse. Read the report of the test gun trials. The guys shooting it…hated the Savage. It was definitely destined to fail in the Army tests against the Colt. The only real problem the Colt 1907 .45 had was “sears” breaking. I was at the Rock Island Arsenal museum 20 years ago and they had about a 100 of the broken sears from the Colt tests. In fact the curator gave me a few of them….which I still have to this day. I even have some Frankford Arsenal .45acp ammo dated “4/06” that was made for the trials. I got it with s/n 25 1911 US Army Colt. The Colt came with 4 first model exposed floorplate lanyard-loop mags in pouches that were loaded with the test ammo (28 rounds). I bought it from the Grandson of the original Army medical officer, that did service with Pershing in Mexico. Who knows, it may be a real story. I wish I had the Colt back….as all the others I’ve had. But, I was in “the business” and everything was for sale. I’ve even sold 12 of the test rounds for $100 a piece, and still have a few left.
        PS….how can I post pictures?

  9. That’s pretty cool….that you found data on the 9.8mm Colt…..and its in Spanish. When I sold the s/n 1…..I gave the guy two boxes of ammo with it. I still have two boxes of Winchester…but they only have one bullet in each box. Neat labels.

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