John M. Browning .45 ACP Hammerless and the 1910 .45 ACP Prototypes

Visit to John Browning Museum in Ogden, UT

26 September 2011

My journey to Ogden, Utah and the John Browning Museum began as a result of several conversations I had with Roy Huntington, editor of the American Handgun magazine. I told Roy about my recreation of the first five hundred 1911 pistols which had been delivered to the US Government in celebration of the 100th anniversary of the adoption of this pistol by the US Ordnance Department. Roy suggested I should also build a recreation of the 1910 prototype. 

To be quite honest, I really didn’t know much about the 1910 prototype pistol. I knew there were several predecessor pistols to the 1911 but I had not studied them. I began to research the 1910 prototype and found it to be very fascinating. Browning built only eight of the 1910 pistols as samples for Colt to show to the various military commands. This allowed Colt to not only showcase the new pistol but also to get a better feel for what the military wanted. The 1910 pistol was a 1911 without a thumb safety. The military made it clear that they wanted some type of safety on the pistol so it could be made safe with the hammer cocked. Browning actually modified two of the 1910 pistols by installing a thumb safety on them. The thumb safety not only locked the sear but also locked the hammer in the full cock position. The military was very happy with this modification.

So as the story goes, the 1911 was born. The testing trials proved the design by shooting 6000 rounds without malfunction or breakage. The 1911 was the first firearm tested by the military to achieve this level of endurance and reliability. The competition among various other prototypes was soundly outclassed by the 1911 and the pistol was adopted by the Ordnance Department in April of 1911. The first deliveries began in January 1912 with the first lot of 500 pistols being delivered to the Ordnance Department.

Once I learned just how important the 1910 pistol was to the birth of the 1911, I became enthusiastic about recreating the pistol. During my initial research on the 1910, I looked on the Internet for more information. Low and behold, I found several web sites that had quite a bit of information on the pistol and even pictures of one of them completely dissembled. I also found out the last one sold at auction brought about 0,000 which made it quite clear I would probably would never get my hands on one to complete my research.

Then a couple of months ago, Roy called me and asked if I would be interested in flying out to Ogden, UT with him to visit the John Browning Museum. My answer was, “Yes, yes, hell yes!” Then he dropped the bomb. He had actually gotten permission to handle the tool-room prototypes of the various pistols that preceded the 1911. Those pistols would have been handled by the MAN HIMSELF! Be still my thumping heart! Not only that, I would be able to actually disassemble the 1910 for close examination and measurements. I couldn’t believe that this once-in-a-lifetime opportunity had presented itself. I couldn’t thank Roy enough.

As I write this, I am on the final leg of my flight to Salt Lake City to meet up with Roy. We will rent a car and drive to Ogden in preparation for our visit to the museum tomorrow. Needless to say, I have been anxiously waiting for this opportunity to actually touch and examine the tool room prototypes which John Browning designed, created and worked on. My entire pistol smithing career has been built around working on and customizing firearms that were either designed by Browning or were takeoffs of handguns he developed. What a special event in my life this trip will be! I will continue this account of my adventure after my visit to the museum.

28 September 2011

As I am on the last leg of my trip, Denver to Omaha, I am still amazed by the visit Roy and I had at the John M. Browning Museum. The museum director, Diana Azevedo, was a dream to work with. She had everything ready that Roy had requested. Diana is a bundle of enthusiastic energy who is totally dedicated to the promotion, preservation, and maintenance of the John M. Browning Museum. It was a true pleasure to work with her.

Diana had the 1910 prototype pistol and the concealed hammer 45 ACP prototype as well as several other 1911 pistols ready for our examination. She provided a spacious, private room with chairs and a desk for our use to examine the pistols. We were escorted into the main area of the museum by Diana to pick up the pistols from the safe where she stored them after they had been removed from their display cases earlier. The amount of Browning firearms on display was fantastic. Not only were there displays with the prototypes of the Hi Power but case after case of rifles, shotguns, and even a special area displaying the military machine guns that John Browning invented. It was almost overwhelming. I just wanted to stop and view every case and read the information cards presented with every firearm. However, Roy and I were on a mission to examine the prototypes of the pistols that led to the 1911 and time was limited. We helped Diana carry the 6 pistols back to the room that had been set aside for us. We were also introduced to Lee and Ward who are super nice guys that volunteer their time to help out at the museum. Both are very knowledgeable about the museum and were especially helpful resources throughout our visit.

Once Roy and I were in the room with the pistols and started to set up the camera equipment, I had to ask Ward, “May I disassemble the pistols to compare the internal parts to the 1911 pistol?” He looked me in the eye and said, “I don’t have a problem with it if you can assure me you can put them back together once you get them apart.” I noted that he had a broad smile on his face! I assured him that not only would I get them put back together but that I would also wipe each part down with oil as I put them back together so that they would not rust. This is critical as the prototype pistols are “in the white” as they were never given any type of protective finish. Needless to say, I was absolutely blown away that I was actually going to be able to disassemble and intimately examine each internal part of two of the rarest prototype pistols on the face of the earth! To tell you that my hands were not shaking a little would be a lie.

After I helped Roy finish setting up his lighting for the photos, I sat down at a small table with the 1910 pistol and began to examine it thoroughly. I immediately noted that there were still file marks in many areas. I also noted that every edge and corner had been lightly rounded. This would have only been done by an individual who understands what makes handling a pistol comfortable, John M Browning. WOW!

While Roy was taking pictures of the concealed hammer pistol, I completed the external examination of the 1910 and began to disassemble it. The 1910 did not have the 1911 style recoil spring plug. The recoil spring plug had a small diameter protrusion sticking out of it that locked into the bottom of the barrel bushing. The barrel bushing could not be turned far enough to remove the recoil spring plug so I had to remove the slide stop to get the top end off of the frame. Once I had the top end off, I could remove the recoil spring guide, recoil spring, and the recoil spring plug. After the recoil spring system was removed, I could turn the barrel bushing to remove it and the barrel. The barrel hood had a small rounded extension that engaged into a corresponding cut in the slide. I guess Browning decided this extra stabilizing tab was not needed on the 1911. It would have also made the barrel and the slide much more difficult to manufacture. The next thing that I noted was the barrel bore had a mirror finish! The Browning shop was manufacturing rifles before they began to make pistols so I guess the mirror finished bore of a pistol barrel would not be any problem for them. The locking lugs completely surrounded the barrel as per his earlier pistols. I noted Browning had rounded the leading edges of the locking lugs on the bottom of the barrel. This was undoubtedly to let the recoil spring bump smoothly over them during recoil. I would guess that the rounded angled contour that is done on the 1911 barrel allows the pistol to function much smoother as well as providing more strength to the barrel. Detailed descriptions of specific parts follow.


The slide was almost a duplicate of the 1911. There was the extra cutout for the small protrusion on the back of the barrel hood. The rear sight was just like the early 1911 but the front sight was a small patridge style located in an angled groove cut into the front of the slide. I would guess that for some reason the barrel locked up higher in the slide on the 1910 so Browning had to cut the angled groove into the front of the slide to make the front sight tall enough to be seen. Without this groove, the front sight would have only been about .030" tall which is much too short to be picked up readily in the rear sight. I wish there would have been time for me to investigate and measure the slide and barrel to determine the differences that made the barrel lock up so high to require the angled groove in the front of the slide.


Remember that the 1910 does not have a thumb safety. This requires a completely different design to retain the grip safety pin, the sear pin, the hammer pin as well as a different slide stop design. There is a side plate on the right rear of the frame that keeps the pins captured. The side plate had the hammer pin riveted into it. The rear tip of the side plate was slightly tapered and had a semicircular cutout. This cutout engages the pin which holds the grip safety in the frame. The grip safety pin had a small head on the left end that drops into a counter sink on the left side of the frame. The right end of the grip safety pin had a groove in it which the slide plate engages. The sear pin has a head on it on the right end that sets into a countersink in the frame. The top of the slide plate is flat. This flat is directly under the slide so that when the slide is on the frame, the slide plate cannot be rotated. When the slide is removed you can rotate the slide plate counter clockwise to unlock the grip safety pin. The mainspring housing has the 1911 style pin in it. To disassemble the frame, you partially remove the mainspring housing to relieve the hammer spring pressure on the hammer, rotate the side plate to allow the removal of the grip safety pin and grip safety. Then, you can remove the mainspring housing completely. The side plate can now be pulled out to the right to remove the hammer. Next, the sear pin can be removed to the right to remove the sear and disconnect. You have to push the magazine catch as far to the right as possible to allow the magazine catch to be rotated until the magazine catch pops out allowing it to be removed from the frame. Next, the trigger can be removed from the frame.

Fire Control Parts

The hammer did not have a wide spur like the 1911. The hammer was hand checkered on a 45 degree angle at about 20 lines per inch (lpi). The interrupter notch and the full cock hooks were 1911 style. The hammer had a large semicircular cutout at the 4 to 7 o’clock area. This cutout is much larger than the 1911 which I think was done to lighten the hammer. It mimics the cutout found on Browning’s lever action rifle hammers. The hammer strut and disconnector are the same as the 1911. The sear is the same shape as the 1911 but much thicker front to back. I have read that there were sear breakages in the earlier guns that Colt submitted for testing so I would assume that Browning “beefed” this one up. The grip safety was pretty much the same as the 1911 except the arm that blocks the trigger was thicker. The mainspring housing was the same as the 1911. The sear spring is the 1911 design except for the tab on the left tine. The early sear springs in the 1911 did not have this tab either. The magazine catch is exactly like the early 1911 with the magazine catch lock having the dimpled head and no screw driver slot. The trigger is made from one piece of steel just like the 1911.

Slide Stop

The slide stop is different from the 1911 in that it has a spring loaded plunger that contacts a stud which is riveted into the frame behind it. Remember, the 1910 did not have a thumb safety so it did not have a plunger tube. Browning used the spring loaded plunger in the slide stop contacting the frame stud to control the movement of the slide stop. The shape of the slide stop was otherwise pretty much like the 1911. The thumb piece on it was flat and did not protrude very far to the side. The thumb piece was hand checkered at a 45 degree angle and approximately 20 lpi. The diameter of the slide stop shaft was .200".

Recoil Spring Guide and Plug

The recoil spring guide was almost a duplicate of the 1911. The only difference I could see was the ears that stick up were not as graceful and pointed as those on the early 1911s.

The recoil spring plug was a thin disk that had a groove in the rear into which the recoil spring was crimped. The front of the plug had a small protrusion that locked into a slot in the bottom of the barrel bushing to keep the bushing from rotating.


The grips were the wooden round top style found on the 1905. The grips were checkered approximately 20 lpi. They had tiny double diamonds around the grip screw escutcheons. The escutcheons were made out of brass and knurled on the outside diameter to keep them in the wood. The grip screws were very small, less than ½ the diameter of the 1911 grip screws. The grip screw bushings in the frame were also much smaller than the 1911. The grip screw bushings were the same diameter from top to bottom.

Firing Pin and Accessories

The firing pin, firing pin stop, firing pin spring, and extractor were exactly like the 1911.


The ejector was the same as the 1911 except that nose that contacts the case was undercut and pointed on the top of the undercut. The ejector was retained with the cross pin contacting the front post exactly like the 1911.


There was no magazine with the pistol but I tried a standard 1911 magazine and it fit. The magazine follower contacted the slide stop and locked the slide open exactly like a 1911.

I hope that this description of the 1910 pistol will be as interesting to you as it was to me. I never dreamed that I would have the opportunity to actually handle and dissemble a 1910. Thanks again to my co-conspirator Roy Huntington. By the way Roy not only photographed the pistol but the internal parts. Please click this link to view the 1910 pistol and parts.

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