Howdy
Here is an Uberti Model 1873 rifle with the side plate removed for a clear view of the toggle link action. In this photo, the lever is all the way up in the shooting position, although the hammer is not cocked, as it would be if the rifle was ready to fire. The toggle links are in their 'locked' position. Note that the three pivot points of the toggle links are in line. Actually, the middle link is ever so slightly out of line, being slightly above the other two. That is part of the design. There are two sets of toggle links, only one is visible in this photo, the other is a mirror image of this one and is directly behind this one. Side note: the Lever Spring at the bottom of the photo is an aftermarket part, it is not the original Uberti leaf spring
This photo also illustrates the 'skeletonized' nature of a toggle link frame. The side plates are separate pieces.
The lever has started to be lowered in this photo. There are three pivot pins for the toggle links. The rear pivot pin is fixed in the frame. The middle pivot pin is attached to an extension of the lever. As the lever is opened, the extension on the lever begins to pull the middle pivot pin down and to the rear. This makes the links start to fold. The front pivot pin is attached to the bolt, and as the links fold, the front pivot pin pulls the bolt straight back..
The lever is now opened all the way. The extension of the lever has pulled the middle pivot pin all the way back and the links are completely folded. The front pivot pin has pulled the bolt all the way back. The bolt extension, which is attached to the bolt, has pushed the hammer all the way back to full cock. A nub on the lever has kicked the lifter bar up and it has in turn raised the brass cartridge elevator. The top of the elevator is visible protruding from the top of the frame.
Notice the two arrows at the lower right corner of the photo. They are pointing to the Lever Safety. This is a feature unique to the Model 1873, the 1860 Henry and the Model 1866 Winchester lacked this feature. The Lever Safety is a single piece with two 'prongs' that extend down through the frame. A spring exerts downward pressure on the Lever Safety. When the lever is open, the Lever Safety pops down and the front portion prevents the trigger from being pulled. When the lever is closed, it shoves the Lever Safety up, allowing the trigger to be pulled. This is not a modern 'lawyer dictated' safety feature only found on modern reproductions of the 1873 Winchester. Early on in production of the 1873, Winchester engineers included this feature because they saw the danger posed if the trigger is accidentally pulled before the toggle links are in the locked position. If the trigger is accidentally pulled before the links are in the 'locked' position, and if a cartridge fires, recoil can drive the bolt back, causing the links to fold. Modern Uberti 1873 replicas have a very strong spring keeping the Lever Safety in the downward position. The force of the spring must be overcome to open the lever. Some Cowboy Action shooters have objected to the Lever Safety and have removed it, or removed the spring. This is a mistake. Without the safety provided by the Lever Safety, an out of battery discharge can allow the bolt to move back forcefully, and the bolt extension, which was only attached to the bolt by the thin pin shown in this photo, can fly back towards the shooters eye when the pin sheared. At the very least, an out of battery discharge with a Model 1873 replica will sting the shooters hand as the lever snaps forward. I was at one match where the lever broke off in the shooter's hand when it snapped forward. Anyway, there are after market spring available if one wants to lessen the strength of the Lever Safety spring.
Interestingly enough, true to the originals, modern replicas of the 1860 Henry and 1866 Winchester lack the Lever Safety. Care must be exercised when shooting them so as not to accidentally brush the trigger while closing the lever.
All the toggle link rifles have an open top frame. The 1873 has a sliding dust cover that slides back the first time the action is worked so empties can be ejected. The dust cover stays back unless manually pushed forward by the shooter. This is a top down photo of my Uberti 1873. It is chambered for the original 44-40 cartridge. The carrier is in the lower position with a round on the carrier. The rim of the next round in the magazine tube can be seen pressing against the round on the carrier. There is no 'cartridge stop' on the carrier of a toggle link rifle, the length of the round in the carrier determines how much of the next round will poke out of the magazine tube. As the carrier rises, a bevel on the carrier shoves the next round back into the magazine tube. If the round on the carrier is too short, the next round will protrude too far, blocking the carrier from rising. These rifles are set up at the factory to feed the standard length cartridges fine, but a round that is too short will block the carrier from rising. When the carrier rises to the feed position, the round is lined up with the chamber and feeds in in a straight line, just like a torpedo being fed into the torpedo tube of a submarine. This is one of the features of toggle link rifles that fast CAS shooters like, it makes for very smooth feeding of a round into the chamber.
The dust cover on an original Winchester Model 1873 rifle in the forward position. Yes, it has been marred where somebody was messing with the badly buggered up screw.
This is a view down from the top of my Uberti 1860 Henry. Notice the lack of a dust cover, the action is always open. A 44-40 round is sitting on the carrier, ready to rise and be fed into the chamber.
An original Winchester Model 1892 chambered for 44-40.
When Winchester bought the patent rights for his single shot rifle, which eventually became the Model 1885 single shot, John Browning already had a design completed for a rifle to replace the Winchester Model 1876. The 1876 was a 'larger version' of the Model 1873, designed for longer, more powerful cartridges, too large for the 1873 action. The 1876 was simply a bigger version of the 1873. It too had a toggle link action. However it was never chambered for 45-70 because the cartridge was simply too long, and the frame would be really, really long to accommodate it. Browning had come up with a completely new design for long 'rifle' caliber cartridges, such as the 45-70. As they did with all his patents for almost the next 20 years, Winchester bought the patent rights to his design. The new rifle was produced as the Model 1886 Winchester.
The Model 1892 Winchester was basically a scaled down version of the Model 1886, for shorter cartridges such as 44-40, 38-40, 32-20, 25-20, and the .218 Bee.
Because of its popularity with the shooting public, the Model 1873 continued to be produced up until 1923. However the model 1892 was stronger, lighter, and less expensive to produce than the Model 1873. I can state that a Model 1873 with a 24" barrel weighs a full pound more than a Model 1892 with a 24" barrel, I have weighed them.
The Model 1892 has two locking lugs that ride in grooves in the frame. There is no dust cover, the bolt itself closes the top of the action when the bolt is closed.
Unlike the toggle link rifles, the frame of both the 1886 and 1892 are one solid piece. In this photo, a Model 1886 is at the top and a Model 1892 is at the bottom. Both have their actions open, with the bolts fully to the rear, cocking the hammers. The levers have pulled the locking lugs straight down. This photo shows how much more massive the 1886 was than the 1892. It also shows the respective cartridges they fired, a 45-70 for the 1886, a 44-40 for the 1892. There was no lever safety in the design of the 1886 or 1892. The lugs would have already locked the bolt in position before the lever was completely closed, so if the trigger was accidentally tripped, the bolt was not going anywhere.
The carrier of the 1886 and 1892 was a tilting carrier. Unlike the carriers of the toggle link rifles, which presented a round straight on to the chamber, a round being fed into the chamber of a 1886 or 1892 rides up into the chamber at a slant. This can sometimes cause feeding problems with cartridges loaded with a bullet with sharp corners, such as semi-wadcutter bullets. Sometimes the corner will hang up on the edge of the chamber as it tries to enter the chamber. Not much different than bullets sometimes jamming riding up the feed ramp of a 1911 pistol. For what it's worth, I always load my ammunition for all my lever rifles with Flat Nosed Round Point bullets.
There you have the differences between a Model 1873 and a Model 1892 in a nutshell. Yes, modern steel makes the modern reproductions of the 1873 rifles stronger than the antiques. But the action is never truly 'locked' as it is with a modern rifle with locking lugs. Think of yourself standing up and some joker comes up behind you and shoves your knees forward. You will collapse like a sack of potatoes. It is the same story with a toggle link rifle, they are never truly 'locked up' when at battery. Also, every Italian firearm made is proofed in government proof houses, to standards that are a little bit stricter than our SAAMI standards. So an Italian 357 Magnum 1873 will have been proofed for modern 357 Magnum ammunition. However, a friend of mine bought a used 357 Magnum Uberti 1873 many years ago. When he got it home he discovered a hairline crack in the frame. He got his money back. No telling what had caused the crack, how many rounds had been put through the rifle by a previous owner, nor how hot they were loaded. But the frame was cracked.