When we last left off on our study of firearm mechanisms, we were still dealing with muzzle-loaders and the percussion cap. While we did study some details about breech-loaders, we really didn't study any of the mechanisms associated with them, aside from the Ferguson rifle. The rise of breechloaders started with the rise of metallic cartridges. In this post, we will study a common breech loader mechanism called the break-action. This is also called top-break or break-barrel action Actually, we did study a bit about break-actions in our discussion about revolver loading mechanisms earlier.
In a break action weapon, the barrels are hinged and break open on top to expose the chamber. One of the well-known examples is a Lefaucheux gun from 1836, which used pinfire cartridges.
There is a lump under the barrels through which a pin passes and the barrels pivot on this pin. There is also a slot cut into the other side of the lump. When the barrels are closed back in place, the user turns the lever in front of the trigger guard, which pushes a projection into the slot, thereby keeping the barrels from moving upwards.
When the barrels are tilted upwards, the user can remove the old cartridges, insert the new cartridges into the barrels and then close and lock the mechanism.
Of course, this mechanism was not always the strongest, but people began to improve upon this basic idea.
In the picture above, we have a W.W. Greener gun using his Treble Wedge-fast mechanism invented in 1865. This gun has three ways to hold the barrel in place. Under the barrels, notice the two projections with slots cut through them. A holding bolt through each one of these slots holds the barrels and prevents them from pivoting, when locked. In addition, notice the top of the barrel also has a projection with a hole through it. When the barrel is locked into place, a cross bolt is pushed through this hole to hold it in place. Each of these holding bolts by itself is capable of holding down the barrels, but the combination of all three together makes the action a strong one indeed.
In the picture above, we have a Greener Improved Treble Wedge-fast mechanism from the top view. When the user pushes the barrels back in place, they can use the long lever and lock all the bolts before firing the weapon.
Of course, it was soon realized that the movement of opening the barrels could also be used to cock the weapon at the same time and this was taken advantage of. Anson and Deeley made the first successful mechanism of this type in 1875, which was followed by other manufacturers such as Westley Richards, Greener, Purdey etc.
The mechanism above is an example of a Greener "Facile Princeps" mechanism. When the barrels are opened, the small lump C pushes one end of hammer A. Since the hammer turns about a pivot, opening the barrel turns the hammer A further back. As the hammer is pushed back, it also compresses the v-shaped spring B. The barrel is opened until the hammer cocks. This happens when A rotates sufficiently for the tip of lever D to hold A as shown in the image above. The weapon can now be loaded with cartridges and closed.
When the trigger is pulled, lever D is pivoted and thereby releases the hammer A. The spring pressure from the v-shaped spring B makes it open and thereby rotates A, which makes the beak of A sharply strike the center of the cartridge and fire it.
It was also realized that the action of the falling barrels could also be used to eject the old cartridges automatically as well. The first example employing this idea was the Needham gun of 1874, but variants of the basic principle were made by several others including Perkes, Anson and Deeley, Baker, Trulock, Ross, Holland & Holland etc.
In the above two images, the extractor lever is clearly visible. When the gun is closed, the extractor sits flush with the barrel. When the gun is opened, the extractor lever pokes out of the barrel and catches the rim of the cartridge and pushes it out of the barrel.
Thus, the user can eject the old cartridges and cock the gun at the same time, merely by the act of breaking open the weapon.
This action is a very compact and straightforward mechanism, which makes the cost of manufacturing pretty low. Since the extractor is part of the barrel, this makes it very suitable for guns that have interchangeable barrels.
There are a ton of firearm myths going around, thanks to the movie industry. This post aims to deal with some of them.
1. Some ceramic guns cannot be detected by airport security equipment.
This myth was chiefly spawned by the movie, "Die Hard 2: Die Harder", starring Bruce Willis. In that movie, his character makes a reference to a mythical Glock 7 pistol, which he claims is "a porcelain gun made in Germany, costs more than your month's salary, and is undetectable by metal detectors." First, Glock never made a model 7, their first pistol was the model 17. Second, Glocks are made in Austria, not Germany. While it is true that a Glock has a fair amount of polymer in its frame, it is a dense material that is visible to X-rays. Also, 85% of the Glock is still made of steel. The same facts are true for any other polymer framed pistol as well, not just Glocks. In fact, Mike Papac, the advisor from Cinema Weaponry, that supplied the firearms for the movie, tried his best to talk them out of that scene. In his own words, "I remember when we did that scene, I tried to talk them out of it. There's no such thing as a gun invisible to metal detectors, and there shouldn't be, but they wouldn't budge. They had it written in the scene and that was that."
2. You can explode anything by shooting it
We've all seen this scene in countless movies. Hero shoots at a car's gas tank and it promptly explodes into a huge ball of flame. Hero shoots at an oxygen tank embedded in a shark's mouth and it promptly blows the great fish to kingdom come. Hero shoots at an oil drum and creates a huge fireball that distracts everyone. Hero shoots at a ...., well you get the idea.
Frankly, if cars exploded into huge fireballs with every tiny puncture or sudden impact, all automobile manufacturers would have been buried in lawsuits years ago. The TV show, "Mythbusters", famously showed how wrong this is in real life. In order to get a gas tank to reliably blow by shooting it, you need to light a fire outside the tank to vaporize the gas inside it to a point that the tank over-pressurizes and then shoot it with a special incendiary bullet! Normal copper or steel-jacketed bullets just don't produce enough sparks to light anything reliably. Well, there's an outside chance that that a steel jacketed bullet may produce enough sparks to start a fire, but this is not a reliable method of ignition. There's a reason people developed special incendiary bullets for specialized applications. And they're not usually available outside the military.
3. Bullets cannot penetrate behind car doors
You always see police take cover behind car doors in the movies. First, even bullets from a 9 mm. handgun will penetrate a single car door, provided they don't hit the steel support beams of the car. Rifles will easily penetrate through the body of the car and come out the other side as well. There are plenty of videos available on the net showing how false this myth is.
4. Machine guns have unlimited ammo.
Watch any action movie where people carry machine guns and you'll notice that they keep firing for a very long time. Time for a reality check:
This is a M-16 fired in full-auto mode. A M-16 fires at 700-950 rounds/minute depending on model (according to Wikipedia), which means it fires between 11.67 and 15.83 rounds/second. A standard magazine contains 20 or 30 rounds, depending on model. At that rate of fire, a 30 round magazine will be emptied in approximately 2-3 seconds, which is about how long it took to empty his magazine in the video. Also note that a full combat load for an US infantryman is 7 magazines (i.e. 210 rounds). This means, if the gentleman above was carrying a standard combat load and fired everything in full auto mode, he could comfortably finish firing his entire supply in under two minutes, including unloading and reloading new magazines. Notice how he switches to firing in semi-auto mode in the second half of the video.
The same is true for other assault rifles as well, not just M-16s. AK-47s have fire rate of 600 rounds/minute, which is 10 rounds/second, which means they'll empty a 30 round mag in 3 seconds flat. A FN FAL has a similar rate of fire at 650-700 rounds/minute. This is why some military rifle models (such as the M16A2 and M16A4 models) don't even support full auto mode as an option and only offer single shot and three-round burst modes.
Now think of the scene in any movie, where the bad guys break into a room brandishing weapons in full-auto mode and proceed to fire for like 30+ seconds and break every glass in sight, all without reloading once. Do you think that could happen in real life, now that you've seen the video clip above?
5. Silencers reduce the weapon's loud "bang" to a soft "phut".
This myth is mostly seen in various spy movies, where the hero carries a silenced pistol or assault rifle and all you hear is a soft "phut" sound and someone falls over and the security flunkie standing 20 feet away hears nothing. Hollywood also shows that not only are silencers almost silent, but also any cylindrical object can be used as a silencer (water bottle, bottle filled with socks etc.) So what is the truth here?
The truth is there are multiple sources of noise when a gun is fired:
Noise of the hammer striking the cartridge.
Noise due to the exploding propellant material and hot gases leaving the barrel.
Noise due to the bullet flying through the air (sonic boom, if the bullet is flying supersonic).
Noise due to ejecting the empty cartridge case and cocking the weapon.
Noise due to bullet striking the target.
Of these, #2 and #3 are the primary sources of loud noise from a firearm.
First, let us consider the noise due to the exploding propellant (which could be gunpowder, cordite, smokeless ball powder etc.). It makes a lot of noise, about 140-160 decibels (dB) worth. By comparison, a loud hard rock or heavy metal band tops out at around 115 dB or so (The author has personally watched concerts by AC/DC, Motorhead, Judas Priest and Iron Maiden from close range. AC/DC has reached 130 dB on occasion and Iron Maiden held the record in 1985). A metal tube isn't going to do much to reduce the noise of exploding gunpowder. This is what an average pistol (Glock model 36) with a silencer sounds like:
Interesting side-fact to notice is that the silencer is actually longer than the pistol is. Notice that there is no soft "phut" noise coming out of the pistol. Think you would fail to hear it over 20 feet away? Now that you've heard that one, here's what a typical automatic submachine gun (Heckler & Koch MP-5) with a silencer attached sounds like:
Notice that it sounds nothing like the movies make it out to be. Mind you, this is a weapon that fires smaller pistol ammunition, not full sized rifle ammunition. There's no soft "phut" sound in this video clip either. As with the previous myth, notice how quickly the shooter goes through her 30 round magazine as well.
So now that we've seen that silencers aren't exactly very silent, what are they for then? Well, they do reduce the sound a bit, from 140-160 dB to 130-145 dB or so, with the quietest ones measuring up to 117 dB. This reduction in loudness level makes it more easier to bear, especially when hearing protection is added. They also reduce the recoil force of the weapon. They also alter the sound signature a bit, so the resulting sound doesn't sound exactly like a gunshot (hence, the Finnish expression, "A silencer does not make a marksman silent, but it makes him invisible.") They are also more useful in closed environments, such as inside a building, where the loud sound and flash could disorient the person shooting the weapon. In the case of supersonic bullets, the sound of the bullet breaking the sound barrier often overshadows the sound of the silenced barrel, so it often misdirects people as to where the shooter is.
Since silencers don't actually make a gun silent, the term itself is a misnomer. In fact, the firearms industry prefers that you refer to them as suppressors instead.
Because of the rapid fire capability of the double-action mechanism, it became the mechanism of choice for new revolvers. Today, most modern revolvers are still double-action. Even Colt, the proponents of single-action pistols, switched to double-action models by the end of the 1800s with their Colt New Service Revolver. Models by Smith & Wesson, Remington, Webley etc. were very popular as well.
By the 1850s or so, metallic cartridges began to replace percussion cap technology. Some revolvers, such as the French-made Lefaucheux, were built to use pinfire cartridges. In 1857, Smith & Wesson introduced their first revolver which used a .22 short rimfire cartridge, also developed by Smith & Wesson. This model was a huge success in the market-place and was responsible for establishing the fame of Smith & Wesson. By the mid 1860s, centerfire cartridges became popular and revolvers began to use them as well (such as the Colt Peacemaker). Most of the early metallic cartridges still used black powder as their propellant, but more powerful smokeless powders started to become popular after 1886 or so and revolver manufacturers began to certify their weapons as safe to be used by smokeless powders as well. This meant using new metallurgical techniques of manufacturing weapons to withstand the higher pressures generated by smokeless powders.
As more powerful cartridges were developed, revolvers were built to fire them as well. In the 1950s, the .44 magnum cartridge, introduced by Elmer Keith and built by Remington, was used by the Sturm-Ruger Blackhawk and the Smith & Wesson Model 29 revolvers. Unusually, the Sturm-Ruger Blackhawk was a single-action revolver, rather than a double-action model. Ruger discovered that after Colt had pulled out its popular Colt Peacemaker (another single-action model) out of the market, there was still some demand for single-action weapons and went on to fill that demand. Company legend at Sturm-Ruger has it that Smith & Wesson were experimenting with the new .44 magnum cartridge in secret, but a Sturm-Ruger employee found the empty cartridge cases in a garbage pile and took one to Bill Ruger and the Blackhawk revolver beat Smith & Wesson's model 29 revolver to the market by several months. The S&W Model 29 didn't sell well initially, but in 1971, the movie "Dirty Harry" came out, with Clint Eastwood's character, "Dirty" Harry Callahan, describing the S&W Model 29 as the "most powerful handgun in the world". While this was not strictly true at this point (the .454 magnum was already developed), this line of movie dialog made the demand for the Model 29 to skyrocket, to the point that dealers were having trouble keeping the Model 29 in stock, even after selling them at triple-price! These days, there are revolvers built to fire even more powerful cartridges, such as the .454 and the .5oo magnum, but the Model 29 sales still remain high, 35 years after the movie came out.
Revolvers used to be the weapon of choice in military and police departments around the world, until modern semi-automatic pistols such as the Colt M1911 became more popular due to shorter reload time and higher capacity of cartridges. Police departments in the United States continued to use revolvers well into the early 1990s, when they began to be replaced by semi-automatic pistols. They are still popular in the civilian market as sporting or hunting weapons. In fact, many trainers recommend new shooters to start off with a revolver.
With all these discussions about revolvers we've had in the last few posts, one significant factor has been common to all of them. The weapons and designs we've looked into have all been handguns! So why have there not been any revolving rifles, the astute reader asks.
Well, there have been some revolving rifles, but they were not very successful. The main issue (and this was also an issue for early revolvers) was a situation called a "chain fire".
Remember that the early revolvers, such as the Colt Paterson and the Walker Colt were using percussion cap technology. Upon firing the weapon, the gunpowder would burn in the chamber and propel the bullet out of the chamber and through the barrel. The flame would then spread out from the front face of the chamber and sometimes go into the next chamber. If the bullet in the next chamber was tight fitting, this wouldn't be a problem, but sometimes users would use a less tightly fitting bullet and there would be gaps between the bullet and the chamber wall. This would sometimes cause gunpowder to leak out of the chamber. As a result, the gunpowder in the next chamber would ignite as well and shoot out its bullet from the side of the revolver, not the barrel. If the user was unlucky enough and used loosely fitting bullets in all chambers, the flame would travel from chamber to chamber and ignite each one, thereby causing extra accidental discharges.
The same situation would sometimes occur if the user used larger (looser) percussion caps on the nipple. When the percussion cap was struck, the flame would travel through the nipple into the chamber and ignite the gunpowder. With a looser percussion cap, some of the flame would travel outside the nipple and through an uncapped nipple or through the loose percussion cap of the next nipple and ignite the gunpowder there.
The result of a chain fire is multiple discharges of the other chambers of a revolving weapon. With a revolver handgun, this is not as much of an issue, besides giving the firer a surprise, because the handgun is usually held at arms length and with one hand only, which is behind the cylinder of the weapon. As the extra chambers fire, the bullets leaving them don't travel as fast because they don't pass through the barrel. They also can't injure the firer, as his hand is behind the cylinder.
Click to enlarge.
On the other hand, with a revolving rifle (such as the 1855 Colt Root model above), the user holds the rifle with two hands and one of these hands is placed in front of the cylinder. So when a chain fire happens, there's a good chance that the user could get his forearm and hand injured by the other accidentally fired bullets. As a matter of fact, the Colt Root model was used for a while during the US civil war by a unit called Berdan's Sharp Shooters. Reports from that era indicate that a number of people set their sleeves on fire from chain fires and that you could tell how long a sharpshooter was in that unit by counting his remaining fingers. The Colt Root was even nicknamed "Colonel Colt's Revolving Wheel of Misfortune". Commanders attempted to counter this by telling their soldiers to hold the rifle in such a way that both hands were behind the cylinder, or by telling them to only load one chamber at a time to prevent chain fires. The 21st Ohio Volunteer Infantry used this rifle with some success in the Battle of Chickamauga, but the problems of chain fire caused the Army board to recommend dropping this weapon altogether.
Later revolving rifles used cartridge technology, where the problem of chain fire did not occur. As a result, revolving rifles made by D.B. Wesson (of Smith & Wesson fame), Remington, Colt Buntline etc. found some use. However, the problem of escaping hot gas from the front of the cylinder burning the user's forearm still remained and this is why they didn't become popular. Another big issue was keeping the weapon clean in combat conditions. Remember that a revolver design has some gaps between the cylinder and the barrel. With a handgun, the weapon can be kept relatively clean by storing it in a holster, when not in use. On the other hand, rifles are carried without a carrying case. In muddy and dusty conditions, keeping the internal mechanisms clean is a lot of work.
However, the idea hasn't entirely vanished. Some auto-cannons, such as the Mauser MK213 and the Aden auto-cannon use the same idea, but they are aircraft guns, not firearms. Some grenade launchers use the same concept as well.
We have devoted the last few posts to studying revolver firing mechanisms. Now we will spend some time in studying revolver loading mechanisms.
The early revolvers such as the first Colt Paterson models of 1836 had a very primitive reloading mechanism. As these revolvers were muzzle-loaders using percussion-cap technology, the user was required to disassemble the gun to reload it. The user would first put the hammer at half-cock, then open a latch in front and pull out the barrel and cylinder from the revolver frame. The user would then fill the cylinder's chambers with gunpowder and a ball in each chamber. Then the user would tamp each ball down with a ramrod. Then the user would assemble the gun back and then attach percussion caps to the back of each chamber. The small revolver on the picture above is a Colt 1836 model.
Obviously, such an operation took a long time. Hence, some people would walk around with already loaded spare cylinders in their pockets. That way, all they had to do was to pull out the barrel and cylinder from the revolver frame, substitute the new pre-loaded cylinder and reassemble the gun.
The Colt Paterson model of 1839 improved on this by putting a loading window on the side of the weapon, near the front of the cylinder. Colt also attached a ramrod on a hinge, on the underside of the barrel. Using this system, the user did not need to disassemble the revolver to reload any longer. Instead the user would put the gunpowder and ball into the chamber that is next to the loading window. Then the user would unhinge the ramrod and use the lever to ram the ball into the chamber. The user would repeat this operation until all the chambers were reloaded. The two crossed revolvers in the picture above are Colt 1839 revolvers.
With the advent of metallic cartridges, the next mechanism that was used was the fixed cylinder/loading gate concept.
In here, there is a hinged loading gate near the back of the cylinder. The gate cover can be slid open and then, metallic cartridges can be removed or loaded one at a time into the loading gate. The cylinder can be rotated after each chamber is loaded, to bring the next chamber in line for reloading. The gate cover is closed after the desired chambers are reloaded. The Colt Peacemaker was one of the weapons that used this reloading mechanism. Since the cylinder is attached to the solid frame of the weapon in both the front and the back, revolvers using this loading mechanism are generally very strong weapons. This is why large caliber revolvers that fire powerful cartridges tend to use this reloading mechanism. The disadvantage of this mechanism is that each chamber needs to be loaded/unloaded one at a time.
The next reloading mechanism we will study is the top-break mechanism. In this mechanism, the revolver is hinged near the front-bottom of the cylinder.
The user can open the revolver as shown in the picture above and load new cartridges in quickly and easily. In fact, many users use a speedloader, which is a simple device that holds the cartridges in a circle corresponding to the chambers of the revolver. A picture of a typical revolver speedloader is shown below.
The user simply puts the speedloader on top of the cylinder and unlocks the speedloader, which drops all the cartridges simultaneously into all the chambers of the cylinder.
In many top-break revolvers, the action of breaking open also pushes an extractor lever upwards, which ejects out all the old cartridges, or moves them far enough out of the cylinder that they can be pulled out easily.
In the picture above, you can see the old cartridges being expelled by the extractor of a Smith and Wesson revolver as it is being opened. In many models, the auto-extractor is powerful enough to eject the fired cartridges, but is not strong enough to completely eject the longer, unfired cartridges. These are merely lifted away from the chambers by the extractor and not ejected out of the weapon completely.
The advantage of the top-break design is that it allows faster reloading as all the chambers can be loaded simultaneously. If the weapon has an auto-extractor, then the reloading becomes even more faster, as the user doesn't need to manually extract the old cartridges. The disadvantage is that the design isn't as strong as the fixed cylinder design and cannot be used for high-powered cartridges.
The next mechanism is the swing-out cylinder mechanism. In this, the cylinder is mounted on a pivot that swings out and down.
Public domain image from wikipedia.com. Click to enlarge.
As can be seen in the picture above, the rod in front of the cylinder unlocks the mechanism and allows it to swing out. The rod can then be pushed in to operate the extractor and eject out the fired cartridges. As with the top-break design, the extractor is designed so that unfired cartridges are not completely ejected from the chambers. Loading can then be done one at a time, or simultaneously using a speedloader. After loading, the cylinder is pushed back to the body of the revolver and then locked in place.
In the above diagram, you can see the close-up of the star-shaped extractor plate. When the revolver is closed, it sits flush with the cylinder. When the extractor plate is pushed away from the cylinder, it catches the rim of all the cartridges loaded in the cylinder and pushes them out of their chambers.
This is a modern design and is much more sturdy than the top-break mechanism. However, it is not as strong as the fixed-cylinder design. On the other hand, it is much faster to reload than a fixed-cylinder model.
In the last few posts, we've studied various types of single-action and double action revolvers. These were not the only types of revolver mechanisms though.
Click image to enlarge
The above image is a Tranter revolver invented by William Tranter. William Tranter used to manufacture the Adams double-action revolver under license and in 1853, he came up with his own invention, a double-trigger, double action revolver. Notice that the distinguishing feature of his revolver is the double trigger. The lower trigger sticks out below the trigger guard and is pulled with the middle finger. When the lower trigger is pulled, it cocks the hammer and rotates the cylinder. Then the user pulls the upper trigger with the forefinger to release the hammer and fire the weapon. If the user decides to fire rapidly, then he/she can pull both triggers simultaneously.
During the US civil war, the Confederates did not have any firearms factories in their territory and hence were forced to import their firearms from other countries. Many Tranter revolvers were imported by them, along with other revolvers such as the Adams and Beaufort-Adams. The Tranter revolvers gained popularity among the Confederates because of their reliability. Tranters were also carried by detectives of the famous Pinkerton detective agency. Pinkerton's men were responsible for the safety of US government officials before the creation of the Secret Service.
William Tranter made a sizable fortune from the sale of various firearms (including his revolvers) and later went on to co-found the Birmingham Small Arms company. This company later moved into manufacturing bicycles, motorcycles and cars. It was once the largest motorcycle manufacturer in the world and its bicycle brand was sold to India's Tube Investments Limited in 1957. Tube Investments still manufactures bicycles in India under the BSA brand.
Another unusual revolver mechanism was invented by the Iver Johnson company of the US. Between 1940 and 1947, they manufactured a revolver with a very special action. If the hammer was down, pulling the trigger would cock the hammer and rotate the cylinder. If the hammer was already cocked, then it would release the hammer and fire the weapon. Therefore, to fire the weapon when the hammer is down, the user would pull the trigger twice.
Another development that has been used since around 1901 or so is the automatic revolver. Basically, the disadvantage of a double action revolver is that it has a longer trigger pull than a single action revolver, because the trigger pull on a double action serves to cock the hammer, rotate the cylinder and release the hammer on a single pull, whereas a single action trigger merely releases the hammer when the trigger is pulled. This leads to a heavier trigger pull and therefore, less accuracy from double-action revolvers.
With an automatic revolver, some of the recoil force from the just fired cartridge is utilized to re-cock the hammer and rotate the cylinder. This results in a revolver that can fire with the speed of a double-action, but with the softer trigger pull of a single-action revolver. The Webley-Fosbury pistol of 1901 had this feature, but it was soon replaced by semi-automatic pistols, which were less expensive. In 1997, a company called Mateba invented the Mateba Unica Auto-revolver that uses the same concept.
In the last few posts, we have been studying single action revolvers, such as the Paterson revolver, the Colt Dragoon and the Peacemaker. With a single action revolver, the trigger only serves to release the hammer. To operate the weapon, the user manually pulls the hammer back, which cocks the weapon and rotates the cylinder to the next chamber. Then the user pulls the trigger to fire.
In the 1850s, another mechanism called the "Double Action" was invented. It all started with the Adams revolver from England. The inventor was one Robert Adams, who was a manager for a London based manufacturer called George & John Deane. He invented a revolver where pulling the trigger cocked the hammer, rotated the chamber and then released the hammer, all with a single trigger pull.
The revolver uses a percussion cap firing mechanism and has a cylinder that has 5 chambers in it. As you may notice, this revolver's hammer does NOT have a spur at the back, so the user cannot thumb the hammer back manually to cock it. Instead, pulling the trigger cocks the hammer back and then releases the hammer to fire it. This means, it has a longer (and harder) trigger pull than a single action revolver like the Colt and Smith & Wesson products of this period. On the other hand, rate of fire is much higher than a single action revolver, because the user doesn't need to cock the hammer separately before pulling the trigger.
The Adams sold fairly decently in England, and was actually approved by the British Small Arms Committee and also for the East India Company as well. In fact, the Deane company even went to the extent of making Adams a partner of the company and renamed themselves from Deane & Deane to Deane, Adams and Deane.
While it was a highly regarded weapon, the revolvers were essentially hand-made. Thus, production was slow and more expensive and quality was also somewhat uneven. This made it lose out to the Colt in the American market. Since the parts were hand fitted in the end, interchangeability was not a strong point for the Adams. It also had no recoil shield in the back of the cylinder, so the user could get their hands dirty caused by blowback from the chambers. The nipples that the percussion caps sat on were also not hardened, so they could sometimes explode prematurely. This revolver was strictly a DAO (Double Action Only) as opposed to a pure double-action revolver. Since it was double-action only, that means the user couldn't pull back the hammer manually. In fact, it even dropped extension on the hammer to prevent users from pulling the hammer back manually. This meant it had a longer trigger pull than a single-action revolver and this led to less accuracy.
The British Ordinance Board studied the Adams revolver along with a few other competing products in 1853, with the view of adopting one for general military use. While there was no firm conclusion, a number of officers bought one as an unofficial standard side-arm and these saw some use in the Crimean War.
The Crimean war saw the first competition between single-action (mostly Colt Navy 1851 model) and the double-action Adams revolver in a real conflict. It was found that the single action Colt was more rugged and reliable than the Adams revolver. However, in the type of fighting experienced in Crimea, the slower thumb-cocking method of the single-actions was seen as less useful compared to the rapid fire capability of the double-action revolvers.
J.G. Crosse of the 88th Regiment of Foot wrote a personal letter to Adams: "I had one of your largest sized Revolver Pistols at the bloody battle of Inkermann, and by some chance got surrounded by the Russians. I then found the advantages of your pistol over that of Colonel Colt's, for had I to cock before each shot I should have lost my life. I should not have had time to cock, as they were too close to me, being only a few yards from me; so close that I was bayoneted through the thigh immediately after shooting the fourth man."
One of the veterans of the Crimean war was Lieutenant Frederick E. B. Beaumont of the Royal Engineers. During the war, he came up with a design that improved the flaws of the Adams revolver. After he was granted a patent, he went to the firm of Deane, Adams and Deane, the makers of the Adams revolver and offered them the rights to manufacture his improved design. The resulting revolver was the Beaumont-Adams revolver.
Like the previous Adams revolver, this one also has a cylinder that holds 5 bullets. It also fires by merely pulling the trigger, which cocks the hammer, rotates the cylinder to the next chamber and then releases the hammer. Unlike its predecessor, this one also has a spur on the back of the hammer. This allows the user to use their thumb to pull back the hammer to cock the weapon, which also rotates the cylinder. Pulling the trigger then releases the hammer. This weapon was the first true double-action revolver as we know it. The Beaumont-Adams also fixed some of the other issues with the Adams, such as hardening the percussion cap nipples. This weapon was adopted as the official revolver of the British Army in 1856.
During the Indian Mutiny, the effectiveness of the Adams and the Beaumont-Adams revolvers came to the forefront again, where not only was the Colt's slowness called into question, but also its perceived lack of stopping power versus the British revolvers. A damning report was submitted by Lt. Col. George Vincent Fosbery: "An officer, who especially prided himself in his pistol shooting, was attacked by a stalwart mutineer armed with a heavy sword. The officer, unfortunately for himself, carried a Colt's Navy pistol of small caliber and fired a sharp-pointed bullet of sixty to the pound and a heavy charge of powder, its range being 600 yards, as I have frequently proved. This he proceeded to empty into the sepoy as soon as he advanced, but having done so, he waited just one second too long to see the effect of his shooting and was cloven to the teeth by his antagonist, who then dropped down and died beside him. My informant told me that five out of the six bullets had struck the sepoy close together in the chest, and all had passed through him and out of his back." Reports like these commonly emerged from the Indian Mutiny and it wasn't long before the double action British revolvers began to grow in popularity because of their rapid firepower and superior stopping power. By the end of 1857, Colt had to close down their factory in London due to dropping sales.
Robert Adams later split from Deane & Deane and went on to found the London Armory company which made several Beaumont-Adams revolvers in calibers like .442, .479, .50, .338, .32 etc. Some were also license-made in the US by the Massachusetts Arms Company, which made holster and pocket-sized models. So many were imported and used by both sides of the Civil war, that the most common double-action revolver used was the Beaumont-Adams.
One of the issues of the Beaumont-Adams was that it still used percussion cap technology. Its replacement in 1880 was the Enfield Mark-I which used centerfire cartridges filled with black-powder. However, the Beaumont-Adams was a revolutionary weapon because it was instrumental in developing the modern double-action, which is still the mechanism of choice in today's revolvers.
The mechanism above is an example of a Greener "Facile Princeps" mechanism. When the barrels are opened, the small lump C pushes one end of hammer A. Since the hammer turns about a pivot, opening the barrel turns the hammer A further back. As the hammer is pushed back, it also compresses the v-shaped spring B. The barrel is opened until the hammer cocks. This happens when A rotates sufficiently for the tip of lever D to hold A as shown in the image above. The weapon can now be loaded with cartridges and closed. 
In the above two images, the extractor lever is clearly visible. When the gun is closed, the extractor sits flush with the barrel. When the gun is opened, the extractor lever pokes out of the barrel and catches the rim of the cartridge and pushes it out of the barrel.
