I think it’s fair to lionize Samuel Colt’s engineering genius and at the same time disparage the Colt’s Patent Firearms Co. I know they're an easy target, so I’ll lionize first, disparage second. I own a 2nd Gen. Colt 1860 Army revolver. I have attached an image of my two fine revolvers, one an unmentionable, below. The 1860 Army was a high water mark for firearms production in its day, the apogee of the art. It was called a single action revolver, which really meant it consisted of a single part, the hammer. The hammer is a lever rotating on a fulcrum called the hammer screw. The lever’s separate ends describe arcs over that rotation, and, since the rotation is limited anything attached to one of its ends goes up and down like a childrens’ seesaw within those limits, depending upon the direction of the lever’s rotation on the hammer screw.
A fine example of how this works is the pawl. The pawl (hand) rotates on a pin inserted into the hammer lobe, one end of the lever above. As the hammer is cocked, the hammer lobe describes an arc upward, and the pawl rotates on its mounting pin and moves linearly up. A spring fastened to the pawl pushes it forward so that as it moves upward it interferes with a toothed wheel, called the cylinder, causing it to rotate on its axis, called the arbor. So the act of cocking the hammer causes the cylinder to rotate also. Now, this would be a useless parlour trick if it happened in isolation, a sort of “Look Maude, an automaton!” a passing marvel, if it did not also open-up the allied idea of timing.
By coordinating the length of travel of the hammer lobe, the length of the pawl, the circumference of the toothed wheel, or ratchet, and the shape and location of the teeth, it is possible to precisely predict exactly where the cylinder will rotate to when the hammer is cocked. That is called timing. By placing a chamber in that location, all around the cylinder, it is possible to provide a load to fall precisely under the hammer with every cocking action. The hammer lobe itself may be made into a ratchet by means of shelves or cuts into its curvature into which a tooth, called the trigger, is made to fit, the whole under the influence of a powerful spring that tries to keep the hammer down and uncocked. Finger pressure on the trigger is necessary to release the spring by removing the tooth from the ratchet, and the hammer falls on the chamber. Incidentally, this also causes the pawl to drop linearly down, ready to once again engage a tooth of the cylinder upon cocking.
So far, so good; but how do you apply limits to these events? How is the cock limited, how is the cylinder registered in its rotation, and does wear, or inertia (the speed of the cocking action) play a role in where the cylinder comes to rest? Again, a matter of timing. A cylinder stop, called a bolt comes into play as an, if not the, essential element of the single action process. The bolt consists of a u-shaped spring having two spring arms, shaped like gentle hooks or “plowhandles,” and has at its apex a solid cylindrical shaft extending perpendicular well-above the plane of the spring arms. The spring arms are drilled transversely and rotate upon a fulcrum called a pinscrew, that fixes it to the revolver frame, and this is acted upon by spring pressure from another flat spring acting also to return the trigger lever.
This is all very clever, but hardly brilliant as it’s merely the application of solid mid-nineteenth-century engineering practice in the newly-industrializing mechanical world of steamships, locomotives, mines, and factories. But here is the particular wrinkle added by Mr. Colt; locating a complex-surfaced, cam-faced pin fixed solidly in the hammer lobe. Upon cocking, the hammer lobe describes an arc; the cam face has a sharp, full edge that tapers down to a flush surface with the rest of the hammer lobe. The full edge catches under one of the bolt plowhandles and drags it upward. This causes it to rotate on its pinscrew and drop the bolt shaft down and out of the way. The cylinder has begun to rotate under the influence of the pawl. As the cocking proceeds the cam face presents less of a full face and more of its taper to the bolt plowhandle. Since another flat spring is pushing the bolt shaft upward, there’s a battle of forces between that spring and the cam pin face against the plowhandle. Eventually the plowhandle will slip over the reducing cam edge and drop while the flat trigger return spring forces the bolt up.
The bolt now strikes the rotating cylinder at the bolt notch raceway, which guides it up and into the bolt notch in the cylinder at precisely the right point to secure the chamber under the fully-cocked hammer for firing. The cylinder ratchet tooth has rotated out of the way of the pawl, which is now also fixed and motionless. Upon dropping the hammer on the loaded chamber, the pawl drops down again, and the hammer lobe rotates down past the bolt plowhandle, the cam pin’s flush edge first, causing the plowhandle to once again slip over and then catch on the full, sharp edge of the cam pin face. The spring tension keeping the plowhandle spring arm in contact with the cam pin face is provided by the other arm pressing against the action cavity sidewall. Translating rotation into linear motion and vice-versa was typical engineering know-how back in the day, but camming action was, I suspect, quite a bit more subtle and exotic, and Mr. Colt appears to have had the ability to reach his mind out just that much further than the rest and so imagine, then provide us with his marvelous single-action revolver.
Now, here is where the disparagement I spoke of at the outset begins. With the single-action process as described came multiple additional opportunities. In particular, my 1860 Army has an ingenious system to ensure safety. In an already slender and compact cylinder, Colt introduced between-chamber safety pins. These are hardened and fit into precision-drilled holes. I believe they are sweated-in, which means that the cylinder is heated to expand it in all dimensions while the pins, which are either chilled or simply left cold are slipped into the holes, which creates an interference fit when the cylinder cools again. The hammer face has a corresponding notch to fit over the safety pin. When the hammer is only very-slightly cocked back, the pawl has not yet engaged the cylinder ratchet teeth, but the bolt has dropped below the water table sufficiently to allow the cylinder to be rotated by hand. The hammer may thus be placed over a safety pin and thumb pressure removed. The gun is unbolted, but locked and safe to carry with six loaded and capped chambers.
It’s my belief that many years after Samuel Colt’s death, the Colt’s Patent Firearms Co. in designing the 1873 Single Action Army knowingly and deliberately dropped this safety system in favor of a simplified alternative, the so-called “safety notch.” The safety notch is what produces the notorious four-clicks of a Colt Peacemaker hammer. It is the first click, and as a safety it’s weakness makes it widely ignored in favor of carrying the arm with the hammer down on an empty chamber; a five-shot revolver.
Now in my mind, Colt’s stood to make a lot of money, a boat load over this simplification of the manufacturing process. They avoided the precision drilling, wear and tear on tools, the heating and sweating-in, and substituted an extra sawcut on the hammer lobe instead. By selling the 1873 at about the price of the 1860 (the 1860 sold for $20 in 1860, then it was reduced to $14.50 by 1865, from Wikipedia; an 1873 sold for about $17.50, from Popular Mechanics, Nov. 23, 2020), their profit margin on each unit must have soared! The America of the 1870’s was the heyday of the Robber Barons and it was the zeitgeist of the times to EXceed.
How could an alternative have been arrived at? A smaller-diameter cartridge than the .45 LC of course (.44-40?); or a slightly-larger cylinder and maybe even a frame-mounted, sprung firing pin. Some combination that would allow either firing pin style to enter the between-chamber holes to lock the piece. That would dispense with the hardened, sweated-in pins, the extra sawcut, and might have saved enough, right there, to cover costs in additional cylinder metal and firing pin structures. The result would have a more or less neutral impact on P&L but provide a safe and useful six-shots! I guess it’s an open question whether the transfer bar mechanism of the unmentionable shown below, itself a modern classic, is a better alternative to a putative Colt mechanism like the one I just speculated about. ;-)
Cheers,
Sir James
A fine example of how this works is the pawl. The pawl (hand) rotates on a pin inserted into the hammer lobe, one end of the lever above. As the hammer is cocked, the hammer lobe describes an arc upward, and the pawl rotates on its mounting pin and moves linearly up. A spring fastened to the pawl pushes it forward so that as it moves upward it interferes with a toothed wheel, called the cylinder, causing it to rotate on its axis, called the arbor. So the act of cocking the hammer causes the cylinder to rotate also. Now, this would be a useless parlour trick if it happened in isolation, a sort of “Look Maude, an automaton!” a passing marvel, if it did not also open-up the allied idea of timing.
By coordinating the length of travel of the hammer lobe, the length of the pawl, the circumference of the toothed wheel, or ratchet, and the shape and location of the teeth, it is possible to precisely predict exactly where the cylinder will rotate to when the hammer is cocked. That is called timing. By placing a chamber in that location, all around the cylinder, it is possible to provide a load to fall precisely under the hammer with every cocking action. The hammer lobe itself may be made into a ratchet by means of shelves or cuts into its curvature into which a tooth, called the trigger, is made to fit, the whole under the influence of a powerful spring that tries to keep the hammer down and uncocked. Finger pressure on the trigger is necessary to release the spring by removing the tooth from the ratchet, and the hammer falls on the chamber. Incidentally, this also causes the pawl to drop linearly down, ready to once again engage a tooth of the cylinder upon cocking.
So far, so good; but how do you apply limits to these events? How is the cock limited, how is the cylinder registered in its rotation, and does wear, or inertia (the speed of the cocking action) play a role in where the cylinder comes to rest? Again, a matter of timing. A cylinder stop, called a bolt comes into play as an, if not the, essential element of the single action process. The bolt consists of a u-shaped spring having two spring arms, shaped like gentle hooks or “plowhandles,” and has at its apex a solid cylindrical shaft extending perpendicular well-above the plane of the spring arms. The spring arms are drilled transversely and rotate upon a fulcrum called a pinscrew, that fixes it to the revolver frame, and this is acted upon by spring pressure from another flat spring acting also to return the trigger lever.
This is all very clever, but hardly brilliant as it’s merely the application of solid mid-nineteenth-century engineering practice in the newly-industrializing mechanical world of steamships, locomotives, mines, and factories. But here is the particular wrinkle added by Mr. Colt; locating a complex-surfaced, cam-faced pin fixed solidly in the hammer lobe. Upon cocking, the hammer lobe describes an arc; the cam face has a sharp, full edge that tapers down to a flush surface with the rest of the hammer lobe. The full edge catches under one of the bolt plowhandles and drags it upward. This causes it to rotate on its pinscrew and drop the bolt shaft down and out of the way. The cylinder has begun to rotate under the influence of the pawl. As the cocking proceeds the cam face presents less of a full face and more of its taper to the bolt plowhandle. Since another flat spring is pushing the bolt shaft upward, there’s a battle of forces between that spring and the cam pin face against the plowhandle. Eventually the plowhandle will slip over the reducing cam edge and drop while the flat trigger return spring forces the bolt up.
The bolt now strikes the rotating cylinder at the bolt notch raceway, which guides it up and into the bolt notch in the cylinder at precisely the right point to secure the chamber under the fully-cocked hammer for firing. The cylinder ratchet tooth has rotated out of the way of the pawl, which is now also fixed and motionless. Upon dropping the hammer on the loaded chamber, the pawl drops down again, and the hammer lobe rotates down past the bolt plowhandle, the cam pin’s flush edge first, causing the plowhandle to once again slip over and then catch on the full, sharp edge of the cam pin face. The spring tension keeping the plowhandle spring arm in contact with the cam pin face is provided by the other arm pressing against the action cavity sidewall. Translating rotation into linear motion and vice-versa was typical engineering know-how back in the day, but camming action was, I suspect, quite a bit more subtle and exotic, and Mr. Colt appears to have had the ability to reach his mind out just that much further than the rest and so imagine, then provide us with his marvelous single-action revolver.
Now, here is where the disparagement I spoke of at the outset begins. With the single-action process as described came multiple additional opportunities. In particular, my 1860 Army has an ingenious system to ensure safety. In an already slender and compact cylinder, Colt introduced between-chamber safety pins. These are hardened and fit into precision-drilled holes. I believe they are sweated-in, which means that the cylinder is heated to expand it in all dimensions while the pins, which are either chilled or simply left cold are slipped into the holes, which creates an interference fit when the cylinder cools again. The hammer face has a corresponding notch to fit over the safety pin. When the hammer is only very-slightly cocked back, the pawl has not yet engaged the cylinder ratchet teeth, but the bolt has dropped below the water table sufficiently to allow the cylinder to be rotated by hand. The hammer may thus be placed over a safety pin and thumb pressure removed. The gun is unbolted, but locked and safe to carry with six loaded and capped chambers.
It’s my belief that many years after Samuel Colt’s death, the Colt’s Patent Firearms Co. in designing the 1873 Single Action Army knowingly and deliberately dropped this safety system in favor of a simplified alternative, the so-called “safety notch.” The safety notch is what produces the notorious four-clicks of a Colt Peacemaker hammer. It is the first click, and as a safety it’s weakness makes it widely ignored in favor of carrying the arm with the hammer down on an empty chamber; a five-shot revolver.
Now in my mind, Colt’s stood to make a lot of money, a boat load over this simplification of the manufacturing process. They avoided the precision drilling, wear and tear on tools, the heating and sweating-in, and substituted an extra sawcut on the hammer lobe instead. By selling the 1873 at about the price of the 1860 (the 1860 sold for $20 in 1860, then it was reduced to $14.50 by 1865, from Wikipedia; an 1873 sold for about $17.50, from Popular Mechanics, Nov. 23, 2020), their profit margin on each unit must have soared! The America of the 1870’s was the heyday of the Robber Barons and it was the zeitgeist of the times to EXceed.
How could an alternative have been arrived at? A smaller-diameter cartridge than the .45 LC of course (.44-40?); or a slightly-larger cylinder and maybe even a frame-mounted, sprung firing pin. Some combination that would allow either firing pin style to enter the between-chamber holes to lock the piece. That would dispense with the hardened, sweated-in pins, the extra sawcut, and might have saved enough, right there, to cover costs in additional cylinder metal and firing pin structures. The result would have a more or less neutral impact on P&L but provide a safe and useful six-shots! I guess it’s an open question whether the transfer bar mechanism of the unmentionable shown below, itself a modern classic, is a better alternative to a putative Colt mechanism like the one I just speculated about. ;-)
Cheers,
Sir James